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VINYLD(1)		     General Commands Manual		       VINYLD(1)

NAME
     vinyld - HTTP accelerator daemon

SYNOPSIS
     vinyld
	    [-a      [name=][listen_address[,PROTO|,option=value,...]]	     [-b
	    [host[:port]|path]] [-C] [-d] [-E extension] [-F]  [-f  config]  [-h
	    type[,options]]  [-I  clifile] [-i identity] [-j jail[,jailoptions]]
	    [-l vsl] [-M address:port] [-n workdir] [-P file]  [-p  param=value]
	    [-r  param[,param...]]   [-S secret-file] [-s [name=]kind[,options]]
	    [-T address[:port]] [-t TTL] [-V] [-W waiter]

     vinyld [-x parameter|vsl|cli|builtin|optstring]

     vinyld [-?]

DESCRIPTION
     The vinyld daemon accepts HTTP requests from clients, passes them on  to  a
     backend  server  and caches the returned documents to better satisfy future
     requests for the same document.

OPTIONS
   Basic options
     -a <[name=][listen_address[,PROTO|,option=value,...]]>
	    Generic syntax to accept client requests on  a  listen_address.  See
	    below for details.

	    Name  is referenced in logs and available to vcl as local.socket. If
	    name is not specified, a with  a  numerical  sequence  ("a0",  "a1",
	    etc.) is used.

	    Any  arguments after the listen_address separated by comma are taken
	    as either an acceptor option=value pair if containing a =, or  as  a
	    PROTO(col) selection otherwise.

	    Valid options depend on the acceptor type, see below.

	    PROTO  can be "HTTP" (the default) or "PROXY".  Both version 1 and 2
	    of the proxy protocol can be used.

	    Multiple -a arguments are allowed.

	    If no -a argument is given, the default -a :80 will  listen  on  all
	    IPv4 and IPv6 interfaces.

     -a <[name=][ip_address][:port][,PROTO]>
	    The ip_address can be a host name ("localhost"), an IPv4 dotted-quad
	    ("127.0.0.1")  or  an  IPv6  address  enclosed  in	square	brackets
	    ("[::1]")

	    The port can be a port number (80), a service name (http), or a port
	    range (80-81). Port ranges are inclusive and cannot overlap. If port
	    is not specified, port 80 (http) is used.

	    At least one of ip_address or port is required.

     -a <[name=][path][,PROTO][,user=name][,group=name][,mode=octal]>
	    (VCL4.1 and higher)

	    Accept connections on a Unix domain socket.  Path must  be	absolute
	    ("/path/to/listen.sock")  or "@" followed by the name of an abstract
	    socket ("@myvinyld").

	    The user, group and mode sub-arguments may be used	to  specify  the
	    permissions  of the socket file -- use names for user and group, and
	    a 3-digit octal value for mode. These sub-arguments do not apply  to
	    abstract sockets.

     -b <[host[:port]|path]>
	    Use  the specified host as backend server. If port is not specified,
	    the default is 8080.

	    If the value of -b begins with /, it is interpreted as the	absolute
	    path of a Unix domain socket to which vinyld connects. In that case,
	    the  value	of -b must satisfy the conditions required for the .path
	    field of a backend declaration,  see  vcl(7).   Backends  with  Unix
	    socket addresses may only be used with VCL versions >= 4.1.

	    -b can be used only once, and not together with f.

     -f config
	    Use  the specified VCL configuration file instead of the builtin de-
	    fault.  See vcl(7) for details on VCL syntax.

	    If a single -f option is used, then the VCL instance loaded from the
	    file is named "boot" and immediately becomes active.  If  more  than
	    one  -f option is used, the VCL instances are named "boot0", "boot1"
	    and so forth, in the order corresponding to the  -f  arguments,  and
	    the last one is named "boot", which becomes active.

	    Either -b or one or more -f options must be specified, but not both,
	    and  they cannot both be left out, unless -d is used to start vinyld
	    in debugging mode. If the empty string is specified as the	sole  -f
	    option,  then vinyld starts without starting the worker process, and
	    the management process will accept CLI commands.  You can also  com-
	    bine  an  empty  -f option with an initialization script (-I option)
	    and the child process will be started if there is an active  VCL  at
	    the end of the initialization.

	    When  used	with  a  relative  file  name, config is searched in the
	    vcl_path. It is possible to set this path prior to using -f  options
	    with  a -p option. During startup, vinyld doesn't complain about un-
	    safe VCL paths: unlike the vinyl-cli(7) that could later be accessed
	    remotely, starting vinyld requires local privileges.

     -n workdir
	    Runtime directory for the shared memory, compiled VCLs etc.

	    In performance critical applications, this directory should be on  a
	    RAM backed filesystem.

	    When running multiple vinyld instances, separate directories need to
	    be used.

	    The default is taken from the VINYL_DEFAULT_N environment variable.

	    Relative paths will be appended to /usr/local/lib/vinyl-cache.

	    If neither VINYL_DEFAULT_N nor -n are present, the value is /usr/lo-
	    cal/lib/vinyl-cache/vinyld.

	    Note: These defaults may be distribution specific.

   Documentation options
     For  these options, vinyld prints information to standard output and exits.
     When a -x option is used, it must be the only option (it outputs documenta-
     tion in reStructuredText, aka RST).

     -?
	Print the usage message.

     -x parameter
	    Print documentation of the runtime parameters (-p options), see List
	    of Parameters.

     -x vsl
	    Print documentation of the tags used in the Vinyld Cache shared mem-
	    ory log, see vsl(7).

     -x cli
	    Print documentation of the command line interface, see vinyl-cli(7).

     -x builtin
	    Print the contents of the default VCL program builtin.vcl.

     -x optstring
	    Print the optstring parameter to getopt(3) to help	writing  wrapper
	    scripts.

   Operations options
     -F     Do	not  fork,  run  in  the foreground. Only one of -F or -d can be
	    specified, and -F cannot be used together with -C.

     -T <address[:port]>
	    Offer a management interface on the specified address and port.  See
	    vinyl-cli(7)  for documentation of the management commands.  To dis-
	    able the management interface use none.

     -M <address:port>
	    Connect to this port and offer the command line interface.	Think of
	    it as a reverse shell. When running with -M and there is no  backend
	    defined the child process (the cache) will not start initially.

     -P file
	    Write the PID of the process to the specified file.

     -i identity
	    Specify the identity of the Vinyl Cache server. This can be accessed
	    using server.identity from VCL.

	    The server identity is used for the received-by field of Via headers
	    generated  by Vinyl Cache. For this reason, it must be a valid token
	    as defined by the HTTP grammar.

	    If not specified the output of gethostname(3) is used, in which case
	    the syntax is assumed to be correct.

     -I clifile
	    Execute the management commands in the file given as clifile  before
	    the worker process starts, see CLI Command File.

     -E extension
	    Load  the  named extension. Extensions are modules (VMODs) which can
	    modify vinyld behavior outside VCL, for example by	adding	storage-
	    or	protocol implementations. Extensions are always also VMODs, even
	    if they do not provide any functionality to VCL, but in  most  cases
	    they will.

	    Any  VMOD  can be loaded as an extension, in which case it is simply
	    pre-loaded at startup and prevented from ever getting unloaded.

	    If extension contains any slashes /, it is taken as an abslute path.
	    Otherwise, for extention ext,  a  vmod_ext.so  is  searched  for  in
	    vmod_path.

	    vinyld startup fails if loading the extension fails for any reason.

   Tuning options
     -t TTL
	    Specifies the default time to live (TTL) for cached objects. This is
	    a shortcut for specifying the default_ttl run-time parameter.

     -p <param=value>
	    Set  the  parameter  specified  by param to the specified value, see
	    List of Parameters for details. This option  can  be  used	multiple
	    times to specify multiple parameters.

     -s <[name=]type[,options]>
	    Use the specified storage backend. See Storage Backend section.

	    This  option  can be used multiple times to specify multiple storage
	    files. Name is referenced in logs, VCL, statistics, etc. If name  is
	    not specified, "s0", "s1" and so forth is used.

     -l <vsl>
	    Specifies  size  of  the space for the VSL records, shorthand for -p
	    vsl_space=<vsl>. Scaling suffixes like 'K' and 'M' can be used up to
	    (G)igabytes. See vsl_space for more information.

   Security options
     -r <param[,param...]>
	    Make the listed parameters read only. This gives the system adminis-
	    trator a way to limit what the Vinyl Cache	CLI  can  do.	Consider
	    making   parameters   such	as  cc_command,  vcc_allow_inline_c  and
	    vmod_path read only as these can potentially  be  used  to	escalate
	    privileges from the CLI.

     -S secret-file
	    Path  to  a  file containing a secret used for authorizing access to
	    the management port. To disable authentication use none.

	    If this argument is not provided, a secret	drawn  from  the  system
	    PRNG will be written to a file called _.secret in the working direc-
	    tory  (see opt_n) with default ownership and permissions of the user
	    having started vinyld.

	    Thus, users wishing to delegate control over  vinyld  will	probably
	    want  to  create  a  custom secret file with appropriate permissions
	    (ie. readable by a unix group to delegate control to).

     -j <jail[,jailoptions]>
	    Specify the jailing mechanism to use. See Jail section.

   Advanced, development and debugging options
     -d     Enables debugging mode: The parent process runs  in  the  foreground
	    with a CLI connection on stdin/stdout, and the child process must be
	    started  explicitly  with  a  CLI  command.  Terminating  the parent
	    process will also terminate the child.

	    Only one of -d or -F can be specified, and -d  cannot  be  used  to-
	    gether with -C.

     -C     Print VCL code compiled to C language and exit. Specify the VCL file
	    to compile with the -f option. Either -f or -b must be used with -C,
	    and -C cannot be used with -F or -d.

     -V     Display the version number and exit. This must be the only option.

     -h <type[,options]>
	    Specifies  the hash algorithm. See Hash Algorithm section for a list
	    of supported algorithms.

     -W waiter
	    Specifies the waiter type to use.

   Hash Algorithm
     The following hash algorithms are available:

     -h critbit
	    self-scaling tree structure. The default  hash  algorithm  in  Vinyl
	    Cache  2.1	and  onwards. In comparison to a more traditional B tree
	    the critbit tree is almost completely lockless. Do not  change  this
	    unless you are certain what you're doing.

     -h simple_list
	    A simple doubly-linked list.  Not recommended for production use.

     -h <classic[,buckets]>
	    A standard hash table. The hash key is the CRC32 of the object's URL
	    modulo  the  size  of  the hash table.  Each table entry points to a
	    list of elements which share the same hash key. The buckets  parame-
	    ter  specifies the number of entries in the hash table.  The default
	    is 16383.

   Storage Backend
     Multiple storage backends (where the cached and in-flight objects are held)
     can be defined, and VCL can pilot	which  store  is  used	by  setting  the
     beresp.storage variable (see man vcl-var for more information).

     The argument format to define storage backends is:

     -s <[name]=kind[,options]>
	    If	name  is omitted, vinyld will name storages sN, starting with s0
	    and incrementing N for every new storage.

	    For kind and options see details below.

     Storages can be used in vcl as storage.name, so, for example  if  myStorage
     was defined by -s myStorage=malloc,5G, it could be used in VCL like so:

	set beresp.storage = storage.myStorage;

     A	special  name  is Transient which is the default storage for uncacheable
     objects as resulting from a pass, hit-for-miss or hit-for-pass.

     If no -s options are given, the default is:

	-s default,100m

     If no Transient storage is defined, the default is an unbound default stor-
     age as if defined as:

	-s Transient=default

     The following storage types and options are available:

     -s <default[,size]>
	    The default storage type resolves to umem where available and malloc
	    otherwise.

     -s <malloc[,size]>
	    malloc is a memory based backend.

     -s <umem[,size]>
	    umem is a storage backend which is more  efficient	than  malloc  on
	    platforms where it is available.

	    See  the  section  on  umem in chapter Storage backends of The Vinyl
	    Users Guide for details.

     -s <file,path[,size[,granularity[,advice]]]>
	    The file backend stores data in a file on disk. The file will be ac-
	    cessed using mmap. Note that this storage provide no  cache  persis-
	    tence.

	    The  path  is  mandatory. If path points to a directory, a temporary
	    file will be created in that directory and immediately unlinked.  If
	    path points to a non-existing file, the file will be created.

	    If	size is omitted, and path points to an existing file with a size
	    greater than zero, the size of that file will be used.  If	not,  an
	    error is reported.

	    Granularity  sets  the allocation block size. Defaults to the system
	    page size or the filesystem block size, whichever is larger.

	    Advice tells the kernel how vinyld expects to use this mapped region
	    so that the kernel can choose the appropriate read-ahead and caching
	    techniques. Possible values are normal, random and sequential,  cor-
	    responding to MADV_NORMAL, MADV_RANDOM and MADV_SEQUENTIAL madvise()
	    advice argument, respectively. Defaults to random.

     -s <persistent,path,size>
	    Persistent	storage. vinyld will store objects in a file in a manner
	    that will secure the survival of most of the objects in the event of
	    a planned or unplanned shutdown of vinyld.	The  persistent  storage
	    backend  has multiple issues with it and will likely be removed from
	    a future version of Vinyl Cache

   Jail
     Vinyl Cache jails are a generalization over various platform specific meth-
     ods to reduce the privileges of vinyld processes. They  may  have	specific
     options. Available jails are:

     -j <solaris[,worker=`privspec`]>
	    Reduce  privileges(5)  for vinyld and sub-processes to the minimally
	    required set. Only available on platforms which have the setppriv(2)
	    call.

	    The optional worker argument can be used to pass a	privilege-speci-
	    fication  (see ppriv(1)) by which to extend the effective set of the
	    vinyld worker process. While extended privileges may be required  by
	    custom vmods, not using the worker option is always more secure.

	    Example to grant basic privileges to the worker process:

	       -j solaris,worker=basic

     -j <linux[,transparent_hugepage=`thp_setting`][,`unixjailoption`...]>
	    Default on Linux platforms, it extends the UNIX jail with Linux-spe-
	    cific mechanisms:

	    * It warns when workdir is not on a tmpfs.

	    * It tries to keep the process dumpable after dropping privileges.

	    * It adds control over the transparent hugepage (THP) setting.

	    thp_setting can take these values:

	    * ignore: Do nothing

	    * enable: Enable THP (see Note below)

	    * disable: Disable THP

	    * try-disable  (default): Try to disable, ignore failure (but emit a
	      warning)

	    Note: Technically, enable is "disable the disable", so it  does  not
	    necessarily  enable THP. The setting names have been chosen to avoid
	    a confusing double negation.

     -j <unix[,user=`user`][,ccgroup=`group`][,workuser=`user`]>
	    Default on all other platforms when vinyld is started with an effec-
	    tive uid of 0 ("as root").

	    With the unix jail mechanism activated, vinyld will switch to an al-
	    ternative user for subprocesses and change the effective uid of  the
	    master process whenever possible.

	    The  optional user argument specifies which alternative user to use.
	    It defaults to vinyl.

	    The optional ccgroup argument specifies a group  to  add  to  vinyld
	    subprocesses requiring access to a c-compiler. There is no default.

	    The  optional workuser argument specifies an alternative user to use
	    for the worker process. It defaults to vcache.

	    The users given for the user and workuser arguments need to have the
	    same primary ("login") group.

	    For users migrating from Varnish Cache, shell  commands  similar  to
	    the  following  may  be used to remove the previous default user and
	    group:

	       userdel varnish || true
	       userdel vcache || true
	       userdel varnishlog || true # to remove reference to varnish group
	       groupdel varnish || true

	    To set up a system for the default users with a  group  name  vinyl,
	    shell commands similar to these may be used:

	       groupadd vinyl
	       useradd -g vinyl -d /nonexistent -s /bin/false \
		 -c "Vinyl Cache Daemon User" vinyl
	       useradd -g vinyl -d /nonexistent -s /bin/false \
		 -c "Vinyl Cache Worker User" vcache
	       useradd -g vinyl -d /nonexistent -s /bin/false \
		 -c "Vinyl Log User" vinyllog

	    Note  that the vinyllog user is not required and only added because,
	    by convention, it may be used to run vinyllog, vinylncsa  and  other
	    VSM/VSL based tools.

     -j none
	    last  resort  jail choice: With jail mechanism none, vinyld will run
	    all processes with the privileges it was started with.

   Management Interface
     If the -T option was specified, vinyld will offer a command-line management
     interface on the specified address and port.  The recommended way	of  con-
     necting to the command-line management interface is through vinyladm(1).

     The commands available are documented in vinyl-cli(7).

   CLI Command File
     The  -I  option makes it possible to run arbitrary management commands when
     vinyld is launched, before the worker process is  started.  In  particular,
     this  is  the  way to load configurations, apply labels to them, and make a
     VCL instance active that uses those labels on startup:

	vcl.load panic /etc/vinyl-cache/panic.vcl
	vcl.load siteA0 /etc/vinyl-cache/siteA.vcl
	vcl.load siteB0 /etc/vinyl-cache/siteB.vcl
	vcl.load siteC0 /etc/vinyl-cache/siteC.vcl
	vcl.label siteA siteA0
	vcl.label siteB siteB0
	vcl.label siteC siteC0
	vcl.load main /etc/vinyl-cache/main.vcl
	vcl.use main

     Every line in the file, including the last line, must be  terminated  by  a
     newline or carriage return or is otherwise considered truncated, which is a
     fatal error.

     If  a  command in the file is prefixed with '-', failure will not abort the
     startup.

     Note that it is necessary to include an explicit vcl.use command to  select
     which VCL should be the active VCL when relying on CLI Command File to load
     the configurations at startup.

RUN TIME PARAMETERS
     Runtime  parameters  can  either  be set during startup with the -p command
     line option for vinyld(1)	or  through  the  CLI  using  the  param.set  or
     param.reset commands. They can be locked during startup with the -r command
     line option.

   Run Time Parameter Units
     There  are different types of parameters that may accept a list of specific
     values, or optionally take a unit suffix.

   bool
     A boolean parameter accepts the values on and off.

     It will also recognize the following values:

     * yes and no

     * true and false

     * enable and disable

   bytes
     A bytes parameter requires one of the following units suffixes:

     * b (bytes)

     * k (kibibytes, 1024 bytes)

     * m (mebibytes, 1024 kibibytes)

     * g (gibibytes, 1024 mebibytes)

     * t (tebibytes, 1024 gibibytes)

     * p (pebibytes, 1024 tebibytes)

     Multiplicator units may be appended with an extra b.  For	example  32k  is
     equivalent to 32kb. Bytes units are case-insensitive.

   seconds
     A duration parameter may accept the following units suffixes:

     * ms (milliseconds)

     * s (seconds)

     * m (minutes)

     * h (hours)

     * d (days)

     * w (weeks)

     * y (years)

     If  the  parameter is a timeout or a deadline, a value of "never" (when al-
     lowed) disables the effect of the parameter.

   Run Time Parameter Flags
     Runtime parameters are marked with shorthand flags to avoid  repeating  the
     same text over and over in the table below. The meaning of the flags are:

     * experimental

       We have no solid information about good/bad/optimal values for this para-
       meter. Feedback with experience and observations are most welcome.

     * delayed

       This  parameter can be changed on the fly, but will not take effect imme-
       diately.

     * restart

       The worker process must be stopped and restarted, before  this  parameter
       takes effect.

     * reload

       The VCL programs must be reloaded for this parameter to take effect.

     * wizard

       Do not touch unless you really know what you're doing.

     * only_root

       Only works if vinyld is running as root.

   Default Value Exceptions on 32 bit Systems
     Be  aware that on 32 bit systems, certain default or maximum values are re-
     duced relative to the values listed below, in order to conserve VM space:

     * workspace_client: 24k

     * workspace_backend: 20k

     * http_resp_size: 8k

     * http_req_size: 12k

     * gzip_buffer: 4k

     * vsl_buffer: 4k

     * vsl_space: 1G (maximum)

     * thread_pool_stack: 64k

   List of Parameters
     This text is produced from the same text you will find in the  CLI  if  you
     use the param.show command:

   accept_filter
     NB: This parameter depends on a feature which is not available on all plat-
     forms.

	* Units: bool

	* Default: on (if your platform supports accept filters)

	* Flags: must_restart

     Enable kernel accept-filters. This may require a kernel module to be loaded
     to have an effect when enabled.

     Enabling  accept_filter  may  prevent some requests to reach Vinyl Cache in
     the first place. Malformed requests may go unnoticed and not  increase  the
     client_req_400 counter. GET or HEAD requests with a body may be blocked al-
     together.

   acceptor_sleep_decay
	* Default: 0.9

	* Minimum: 0

	* Maximum: 1

	* Flags: experimental

     If we run out of resources, such as file descriptors or worker threads, the
     acceptor will sleep between accepts.  This parameter (multiplicatively) re-
     duce  the	sleep  duration for each successful accept. (ie: 0.9 = reduce by
     10%)

   acceptor_sleep_incr
	* Units: seconds

	* Default: 0.000

	* Minimum: 0.000

	* Maximum: 1.000

	* Flags: experimental

     If we run out of resources, such as file descriptors or worker threads, the
     acceptor will sleep between  accepts.   This  parameter  control  how  much
     longer we sleep, each time we fail to accept a new connection.

   acceptor_sleep_max
	* Units: seconds

	* Default: 0.050

	* Minimum: 0.000

	* Maximum: 10.000

	* Flags: experimental

     If we run out of resources, such as file descriptors or worker threads, the
     acceptor will sleep between accepts.  This parameter limits how long it can
     sleep between attempts to accept new connections.

   auto_restart
	* Units: bool

	* Default: on

     Automatically restart the child/worker process if it dies.

   backend_idle_timeout
	* Units: seconds

	* Default: 60.000

	* Minimum: 1.000

     Timeout before we close unused backend connections.

   backend_local_error_holddown
	* Units: seconds

	* Default: 10.000

	* Minimum: 0.000

	* Flags: experimental

     When  connecting  to backends, certain error codes (EADDRNOTAVAIL, EACCESS,
     EPERM) signal a local resource shortage or configuration  issue  for  which
     retrying connection attempts may worsen the situation due to the complexity
     of the operations involved in the kernel.	This parameter prevents repeated
     connection attempts for the configured duration.

   backend_remote_error_holddown
	* Units: seconds

	* Default: 0.250

	* Minimum: 0.000

	* Flags: experimental

     When  connecting  to  backends,  certain error codes (ECONNREFUSED, ENETUN-
     REACH) signal fundamental connection issues such as the backend not accept-
     ing connections or routing problems for which repeated connection	attempts
     are considered useless This parameter prevents repeated connection attempts
     for the configured duration.

   backend_wait_limit
	* Default: 0

	* Minimum: 0

	* Flags: experimental

     Maximum number of transactions that can queue waiting for a backend connec-
     tion  to become available.  This default of 0 (zero) means that there is no
     transaction queueing. VCL can override this default value for each backend.

     Note that this feature must be used with caution, as it can  cause  threads
     to pile up and increase response times.

   backend_wait_timeout
	* Units: seconds

	* Default: 0.000

	* Minimum: 0.000

	* Flags: timeout, experimental

     When a backend has no connections available for a transaction, the transac-
     tion can be queued (see backend_wait_limit) to wait for a connection.  This
     is  the  default  time that the transaction will wait before giving up. VCL
     can override this default value for each backend.

     It is strongly advised to never set this higher than a couple of seconds.

   ban_any_variant
	* Units: checks

	* Default: 0

	* Minimum: 0

     Maximum number of possibly non matching variants that we  evaluate  against
     the ban list during a lookup.  Setting this to 0 means that only the match-
     ing variants will be evaluated against the current ban list.

   ban_cutoff
	* Units: bans

	* Default: 0

	* Minimum: 0

	* Flags: experimental

     Expurge  long  tail content from the cache to keep the number of bans below
     this value. 0 disables.

     When this parameter is set to a non-zero value, the ban lurker continues to
     work the ban list as usual top to bottom, but when it reaches the	ban_cut-
     off-th  ban,  it  treats  all objects as if they matched a ban and expunges
     them from cache. As actively used objects get tested against the  ban  list
     at request time and thus are likely to be associated with bans near the top
     of  the  ban  list,  with	ban_cutoff, least recently accessed objects (the
     "long tail") are removed.

     This parameter is a safety net to avoid bad response times due to bans  be-
     ing  tested at lookup time. Setting a cutoff trades response time for cache
     efficiency.    The     recommended     value     is     proportional     to
     rate(bans_lurker_tests_tested) / n_objects while the ban lurker is working,
     which  is the number of bans the system can sustain. The additional latency
     due  to  request  ban  testing  is   in   the   order   of   ban_cutoff   /
     rate(bans_lurker_tests_tested).	      For	   example,	     for
     rate(bans_lurker_tests_tested) = 2M/s and a tolerable latency of  100ms,  a
     good value for ban_cutoff may be 200K.

   ban_dups
	* Units: bool

	* Default: on

     Eliminate older identical bans when a new ban is added.  This saves CPU cy-
     cles  by  not comparing objects to identical bans.  This is a waste of time
     if you have many bans which are never identical.

   ban_lurker_age
	* Units: seconds

	* Default: 60.000

	* Minimum: 0.000

     The ban lurker will ignore bans until they are this old.	When  a  ban  is
     added,  the  active  traffic  will  be  tested against it as part of object
     lookup.  Because many applications issue bans  in	bursts,  this  parameter
     holds the ban-lurker off until the rush is over.  This should be set to the
     approximate time which a ban-burst takes.

   ban_lurker_batch
	* Default: 1000

	* Minimum: 1

     The  ban  lurker  sleeps  ${ban_lurker_sleep} after examining this many ob-
     jects.  Use this to pace the ban-lurker if it eats too many resources.

   ban_lurker_holdoff
	* Units: seconds

	* Default: 0.010

	* Minimum: 0.000

	* Flags: experimental

     How long the ban lurker sleeps when giving way to lookup due to  lock  con-
     tention.

   ban_lurker_sleep
	* Units: seconds

	* Default: 0.010

	* Minimum: 0.000

     How long the ban lurker sleeps after examining ${ban_lurker_batch} objects.
     Use  this to pace the ban-lurker if it eats too many resources.  A value of
     zero will disable the ban lurker entirely.

   between_bytes_timeout
	* Units: seconds

	* Default: 60.000

	* Minimum: 0.000

	* Flags: timeout

     We only wait for this many seconds between bytes received from the  backend
     before giving up the fetch.  VCL values, per backend or per backend request
     take precedence.  This parameter does not apply to pipe'ed requests.

   cc_command
     NB:  The actual default value for this parameter depends on the Vinyl Cache
     build environment and options.

	* Default: exec $CC $CFLAGS %w -shared -o %o %s

	* Flags: must_reload

     The command used for compiling the C source code to  a  dlopen(3)	loadable
     object. The following expansions can be used:

     * %s: the source file name

     * %o: the output file name

     * %w: the cc_warnings parameter

     * %d: the raw default cc_command

     * %D: the expanded default cc_command

     * %n: the working directory (-n option)

     * %%: a percent sign

     Unknown percent expansion sequences are ignored, and to avoid future incom-
     patibilities percent characters should be escaped with a double percent se-
     quence.

     The  %d  and %D expansions allow passing the parameter's default value to a
     wrapper script to perform additional processing.

   cc_warnings
     NB: The actual default value for this parameter depends on the Vinyl  Cache
     build environment and options.

	* Default: -Wall -Werror

	* Flags: must_reload

     Warnings  used when compiling the C source code with the cc_command parame-
     ter. By default, VCL is compiled with the same set  of  warnings  as  Vinyl
     Cache itself.

   cli_limit
	* Units: bytes

	* Default: 64k

	* Minimum: 128b

	* Maximum: 99999999b

     Maximum  size of CLI response.  If the response exceeds this limit, the re-
     sponse code will be 201 instead of 200 and the last line will indicate  the
     truncation.

   cli_timeout
	* Units: seconds

	* Default: 60.000

	* Minimum: 0.000

	* Flags: timeout

     Timeout for the child's replies to CLI requests.

   clock_skew
	* Units: seconds

	* Default: 10

	* Minimum: 0

     How much clockskew we are willing to accept between the backend and our own
     clock.

   clock_step
	* Units: seconds

	* Default: 1.000

	* Minimum: 0.000

     How much observed clock step we are willing to accept before we panic.

   connect_timeout
	* Units: seconds

	* Default: 3.500

	* Minimum: 0.000

	* Flags: timeout

     Default  connection timeout for backend connections. We only try to connect
     to the backend for this many seconds before giving  up.  VCL  can	override
     this default value for each backend and backend request.

   critbit_cooloff
	* Units: seconds

	* Default: 180.000

	* Minimum: 60.000

	* Maximum: 254.000

	* Flags: wizard

     How long the critbit hasher keeps deleted objheads on the cooloff list.

   debug
	* Default: none

     Enable/Disable various kinds of debugging.

	none   Disable all debugging

     Use +/- prefix to set/reset individual bits:

	req_state
	       VSL Request state engine

	workspace
	       VSL Workspace operations

	waitinglist
	       VSL Waitinglist events

	syncvsl
	       Make VSL synchronous

	hashedge
	       Edge cases in Hash

	vclrel
	       Rapid VCL release

	lurker
	       VSL Ban lurker

	esi_chop
	       Chop ESI fetch to bits

	flush_head
	       Flush after http1 head

	vtc_mode
	       Vinyltest Mode

	witness
	       Emit WITNESS lock records

	vsm_keep
	       Keep the VSM file on restart

	slow_acceptor
	       Slow down Acceptor

	h2_nocheck
	       Disable various H2 checks

	vmod_so_keep
	       Keep copied VMOD libraries

	processors
	       Fetch/Deliver processors

	protocol
	       Protocol debugging

	vcl_keep
	       Keep VCL C and so files

	lck    Additional lock statistics

   default_grace
	* Units: seconds

	* Default: 10s

	* Minimum: 0.000

	* Flags: obj_sticky

     Default grace period.  We will deliver an object this long after it has ex-
     pired, provided another thread is attempting to get a new copy.

   default_keep
	* Units: seconds

	* Default: 0s

	* Minimum: 0.000

	* Flags: obj_sticky

     Default  keep period.  We will keep a useless object around this long, mak-
     ing it available for conditional backend fetches.	That means that the  ob-
     ject will be removed from the cache at the end of ttl+grace+keep.

   default_ttl
	* Units: seconds

	* Default: 2m

	* Minimum: 0.000

	* Flags: obj_sticky

     The TTL assigned to objects if neither the backend nor the VCL code assigns
     one.

   experimental
	* Default: none

     Enable/Disable experimental features.

	none   Disable all experimental features

     Use +/- prefix to set/reset individual bits:

	drop_pools
	       Drop thread pools

   feature
	* Default: none,+https_scheme,+validate_headers,+vcl_req_reset

     Enable/Disable various minor features.

	default
	       Set default value (deprecated: use param.reset)

	none   Disable all features.

     Use +/- prefix to enable/disable individual feature:

	http2  Enable HTTP/2 protocol support.

	short_panic
	       Short panic message.

	no_coredump
	       No coredumps.  Must be set before child process starts.

	https_scheme
	       Extract	host  from  full  URI in the HTTP/1 request line, if the
	       scheme is https.

	http_date_postel
	       Tolerate non compliant timestamp headers  like  Date,  Last-Modi-
	       fied, Expires etc.

	esi_ignore_https
	       Convert <esi:include src"https://... to http://...

	esi_disable_xml_check
	       Allow ESI processing on non-XML ESI bodies

	esi_ignore_other_elements
	       Ignore XML syntax errors in ESI bodies.

	esi_remove_bom
	       Ignore UTF-8 BOM in ESI bodies.

	esi_include_onerror
	       Parse the onerror attribute of <esi:include> tags.

	wait_silo
	       Wait  for  persistent silos to completely load before serving re-
	       quests.

	validate_headers
	       Validate all header set operations to conform to RFC9110  section
	       5.5.

	busy_stats_rate
	       Make busy workers comply with thread_stats_rate.

	trace  Enable  VCL  tracing  by default (enable (be)req.trace). Required
	       for tracing vcl_init / vcl_fini

	vcl_req_reset
	       Stop processing client VCL once the client  is  gone.  When  this
	       happens MAIN.req_reset is incremented.

   fetch_chunksize
	* Units: bytes

	* Default: 16k

	* Minimum: 4k

	* Flags: experimental

     The  default  chunksize used by fetcher. This should be bigger than the ma-
     jority of objects with short TTLs.  Internal  limits  in  the  storage_file
     module makes increases above 128kb a dubious idea.

   fetch_maxchunksize
	* Units: bytes

	* Default: 0.25G

	* Minimum: 64k

	* Flags: experimental

     The  maximum chunksize we attempt to allocate from storage. Making this too
     large may cause delays and storage fragmentation.

   first_byte_timeout
	* Units: seconds

	* Default: 60.000

	* Minimum: 0.000

	* Flags: timeout

     Default timeout for receiving first byte from backend.  We  only  wait  for
     this  many  seconds  for the first byte before giving up.	VCL can override
     this default value for each backend and backend  request.	 This  parameter
     does not apply to pipe'ed requests.

   gzip_buffer
	* Units: bytes

	* Default: 32k

	* Minimum: 2k

	* Flags: experimental

     Size  of  malloc  buffer used for gzip processing.  Size of buffer used for
     gzip processing.  These buffers are used for in-transit data, for	instance
     gunzip'ed	data  being sent to a client. Making this space to small results
     in more overhead, writes to sockets etc, making it too big is probably just
     a waste of memory.  Gzip buffers are allocated from Transient storage.

   gzip_level
	* Default: 6

	* Minimum: 0

	* Maximum: 9

     Gzip compression level: 0=debug, 1=fast, 9=best

   gzip_memlevel
	* Default: 8

	* Minimum: 1

	* Maximum: 9

     Gzip memory level 1=slow/least, 9=fast/most compression.  Memory impact  is
     1=1k, 2=2k, ... 9=256k.

   h2_header_table_size
	* Units: bytes

	* Default: 4k

	* Minimum: 0b

     HTTP2  header table size.	This is the size that will be used for the HPACK
     dynamic decoding table.

     The value of this parameter defines SETTINGS_HEADER_TABLE_SIZE in the  ini-
     tial  SETTINGS  frame sent to the client when a new HTTP2 session is estab-
     lished.

   h2_initial_window_size
	* Units: bytes

	* Default: 65535b

	* Minimum: 65535b

	* Maximum: 2147483647b

     HTTP2 initial flow control window size.

     The value of this parameter  defines  SETTINGS_INITIAL_WINDOW_SIZE  in  the
     initial  SETTINGS	frame sent to the client when a new HTTP2 session is es-
     tablished.

   h2_max_concurrent_streams
	* Units: streams

	* Default: 100

	* Minimum: 0

     HTTP2 Maximum number of concurrent streams.  This is the number of requests
     that can be active at the same time for a single HTTP2 connection.

     The value of this parameter defines SETTINGS_MAX_CONCURRENT_STREAMS in  the
     initial  SETTINGS	frame sent to the client when a new HTTP2 session is es-
     tablished.

   h2_max_frame_size
	* Units: bytes

	* Default: 16k

	* Minimum: 16k

	* Maximum: 16777215b

     HTTP2 maximum per frame payload size we are willing to accept.

     The value of this parameter defines SETTINGS_MAX_FRAME_SIZE in the  initial
     SETTINGS frame sent to the client when a new HTTP2 session is established.

   h2_max_header_list_size
	* Units: bytes

	* Default: 0b

	* Minimum: 0b

	* Maximum: 2147483647b

     HTTP2  maximum  size  of an uncompressed header list. This parameter is not
     mapped to SETTINGS_MAX_HEADER_LIST_SIZE in the initial SETTINGS frame,  the
     http_req_size parameter is instead.

     The  http_req_size advises HTTP2 clients of the maximum size for the header
     list. Exceeding http_req_size results in a reset  stream  after  processing
     the    HPACK    block   to   preserve   the   connection,	 but   exceeding
     h2_max_header_list_size results in the HTTP2 connection going away  immedi-
     ately.

     If  h2_max_header_list_size  is lower than http_req_size, it has no effect,
     except for the special value zero interpreted as 150% of http_req_size.

   h2_rapid_reset
	* Units: seconds

	* Default: 1.000

	* Minimum: 0.000

	* Flags: delayed, experimental

     The upper threshold for how soon an  http/2  RST_STREAM  frame  has  to  be
     parsed  after a HEADERS frame for it to be treated as suspect and subjected
     to the rate limits specified by h2_rapid_reset_limit and h2_rapid_reset_pe-
     riod.  Changes to this parameter affect the default for new HTTP2 sessions.
     vmod_h2(3) can be used to adjust it from VCL.

   h2_rapid_reset_limit
	* Default: 100

	* Minimum: 0

	* Flags: delayed, experimental

     HTTP2 RST Allowance.  Specifies the maximum number of allowed stream resets
     issued by a client over a time period  before  the  connection  is  closed.
     Setting  this parameter to 0 disables the limit.  Changes to this parameter
     affect the default for new HTTP2 sessions. vmod_h2(3) can be used to adjust
     it from VCL.

   h2_rapid_reset_period
	* Units: seconds

	* Default: 60.000

	* Minimum: 1.000

	* Flags: delayed, experimental, wizard

     HTTP2 sliding window duration for h2_rapid_reset_limit.   Changes	to  this
     parameter affect the default for new HTTP2 sessions. vmod_h2(3) can be used
     to adjust it from VCL.

   h2_rx_window_increment
	* Units: bytes

	* Default: 1M

	* Minimum: 1M

	* Maximum: 1G

	* Flags: wizard

     HTTP2  Receive Window Increments.	How big credits we send in WINDOW_UPDATE
     frames Only affects incoming request bodies (ie: POST, PUT etc.)

   h2_rx_window_low_water
	* Units: bytes

	* Default: 10M

	* Minimum: 65535b

	* Maximum: 1G

	* Flags: wizard

     HTTP2 Receive Window low water mark.  We try to keep the  window  at  least
     this big Only affects incoming request bodies (ie: POST, PUT etc.)

   h2_rxbuf_storage
	* Default: Transient

	* Flags: must_restart

     The name of the storage backend that HTTP/2 receive buffers should be allo-
     cated from.

   h2_window_timeout
	* Units: seconds

	* Default: 5.000

	* Minimum: 0.000

	* Flags: timeout, wizard

     HTTP2 time limit without window credits. How long a stream may wait for the
     client to credit the window and allow for more DATA frames to be sent.

   http1_iovs
	* Units: struct iovec (=16 bytes)

	* Default: 64

	* Minimum: 5

	* Maximum: 1024

	* Flags: wizard

     Number  of io vectors to allocate for HTTP1 protocol transmission.  A HTTP1
     header needs 7 + 2 per HTTP header field.	Allocated from workspace_thread.
     This parameter affects only io vectors used for client delivery.  For back-
     end fetches, the maximum number of io vectors (up to IOV_MAX)  is allocated
     from available workspace_thread memory.

   http_gzip_support
	* Units: bool

	* Default: on

     Enable gzip support. When enabled Vinyl Cache request compressed objects
     from the backend and store them compressed. If a client does not support
     gzip encoding Vinyl Cache will uncompress compressed objects on demand.
     Vinyl Cache will also rewrite the Accept-Encoding header of clients indi-
     cating support for gzip to:
	    Accept-Encoding: gzip

     Clients that do not support gzip will have their Accept-Encoding header re-
     moved. For more information on how gzip is implemented please see the chap-
     ter on gzip in the Vinyl Cache reference.

     When  gzip  support  is   disabled   the	variables   beresp.do_gzip   and
     beresp.do_gunzip have no effect in VCL.

   http_max_hdr
	* Units: header lines

	* Default: 64

	* Minimum: 32

	* Maximum: 65535

     Maximum	 number     of	   HTTP     header    lines    we    allow    in
     {req|resp|bereq|beresp}.http (obj.http is autosized to the exact number  of
     headers).	 Cheap,  ~20 bytes, in terms of workspace memory.  Note that the
     first line occupies five header lines.

   http_range_support
	* Units: bool

	* Default: on

     Enable support for HTTP Range headers.

   http_req_hdr_len
	* Units: bytes

	* Default: 8k

	* Minimum: 40b

     Maximum length of any HTTP client request header we will allow.  The  limit
     is inclusive its continuation lines.

   http_req_overflow_status
	* Units: HTTP status code or 0 to disable

	* Default: 0

	* Minimum: 400

	* Maximum: 500

     HTTP  status  code to be returned if http_req_size is exceeded. The default
     value of 0 closes the connection silently without sending a HTTP  response.
     Note that there is no standard HTTP status which exactly matches the imple-
     mentation	of http_req_size. 414 applies to the URL only, while 413 applies
     to the request body. 400 is probably the least incorrect alternative  value
     to sending no response at all (0). It can also be seen as an internal error
     on the Vinyl Cache side due to configured limits, so 500 is also allowed.

   http_req_size
	* Units: bytes

	* Default: 32k

	* Minimum: 0.25k

     Maximum number of bytes of HTTP client request we will deal with. This is a
     limit on all bytes up to the double blank line which ends the HTTP request.
     The  memory  for the request is allocated from the client workspace (param:
     workspace_client) and this parameter limits how much of that the request is
     allowed to take up.

     For HTTP2 clients, it is advertised as MAX_HEADER_LIST_SIZE in the  initial
     SETTINGS frame.

   http_resp_hdr_len
	* Units: bytes

	* Default: 8k

	* Minimum: 40b

     Maximum  length  of  any  HTTP  backend response header we will allow.  The
     limit is inclusive its continuation lines.

   http_resp_size
	* Units: bytes

	* Default: 32k

	* Minimum: 0.25k

     Maximum number of bytes of HTTP backend response we will deal  with.   This
     is a limit on all bytes up to the double blank line which ends the HTTP re-
     sponse.   The  memory  for the response is allocated from the backend work-
     space (param: workspace_backend) and this parameter limits how much of that
     the response is allowed to take up.

   idle_send_timeout
	* Units: seconds

	* Default: 60.000

	* Minimum: 0.000

	* Maximum: 3600.000

	* Flags: timeout, delayed

     Send timeout for individual pieces of data on client connections.	May  get
     extended if 'send_timeout' applies.

     When this timeout is hit, the session is closed.

     See  the man page for setsockopt(2) or socket(7) under SO_SNDTIMEO for more
     information.

   listen_depth
	* Units: connections

	* Default: 1024

	* Minimum: 0

	* Flags: must_restart

     Listen queue depth.

   lru_interval
	* Units: seconds

	* Default: 2.000

	* Minimum: 0.000

	* Flags: experimental

     Grace period before object moves on LRU list.  Objects are  only  moved  to
     the  front of the LRU list if they have not been moved there already inside
     this timeout period.  This reduces the amount of lock operations  necessary
     for LRU list access.

   max_esi_depth
	* Units: levels

	* Default: 5

	* Minimum: 0

     Maximum depth of esi:include processing.

   max_restarts
	* Units: restarts

	* Default: 4

	* Minimum: 0

	* Flags: delayed

     Upper limit on how many times a request can restart.

   max_retries
	* Units: retries

	* Default: 4

	* Minimum: 0

	* Flags: delayed

     Upper limit on how many times a backend fetch can retry.

   max_vcl
	* Default: 100

	* Minimum: 0

     Threshold of loaded VCL programs.	(VCL labels are not counted.)  Parameter
     max_vcl_handling determines behaviour.

   max_vcl_handling
	* Default: 1

	* Minimum: 0

	* Maximum: 2

     Behaviour when attempting to exceed max_vcl loaded VCL.

     * 0 - Ignore max_vcl parameter.

     * 1 - Issue warning.

     * 2 - Refuse loading VCLs.

   nuke_limit
	* Units: allocations

	* Default: 50

	* Minimum: 0

	* Flags: experimental

     Maximum  number  of objects we attempt to nuke in order to make space for a
     object body.

   panic_buffer
	* Units: bytes

	* Default: 64k

	* Minimum: 4k

	* Maximum: 10M

	* Flags: must_restart

     Size of the panic message buffer.	The panic buffer  is  allocated  in  the
     working  directory  as  memory  shared  between  the  management and worker
     process, so sufficient working directory space should be accounted  for  if
     this  value  is  adjusted.  Panic	messages are truncated to the configured
     size.

   pcre2_depth_limit
	* Default: 20

	* Minimum: 1

     The recursion depth-limit for the internal match logic in a pcre2_match().

     (See: pcre2_set_depth_limit() in pcre2 docs.)

     This puts an upper limit on the amount of stack used by PCRE2  for  certain
     classes of regular expressions.

     We  have set the default value low in order to prevent crashes, at the cost
     of possible regexp matching failures.

     Matching failures will show up in the log as VCL_Error messages.

   pcre2_jit_compilation
	* Units: bool

	* Default: on

     Use the pcre2 JIT compiler if available.

   pcre2_match_limit
	* Default: 10000

	* Minimum: 1

     The limit	for  the  number  of  calls  to  the  internal	match  logic  in
     pcre2_match().

     (See: pcre2_set_match_limit() in pcre2 docs.)

     This  parameter  limits  how  much CPU time regular expression matching can
     soak up.

   ping_interval
	* Units: seconds

	* Default: 3

	* Minimum: 0

	* Flags: must_restart

     Interval between pings from parent to child.  Zero will disable pinging en-
     tirely, which makes it possible to attach a debugger to the child.

   pipe_sess_max
	* Units: connections

	* Default: 0

	* Minimum: 0

     Maximum number of sessions dedicated to pipe transactions.

   pipe_task_deadline
	* Units: seconds

	* Default: 0.000

	* Minimum: 0.000

	* Flags: timeout

     Deadline for PIPE sessions. Regardless of activity in either direction  af-
     ter this many seconds, the session is closed.

   pipe_timeout
	* Units: seconds

	* Default: 60.000

	* Minimum: 0.000

	* Flags: timeout

     Idle timeout for PIPE sessions. If nothing have been received in either di-
     rection for this many seconds, the session is closed.

   pool_req
	* Default: 10,100,10

     Parameters for per worker pool request memory pool.

     The three numbers are:

	min_pool
	       minimum size of free pool.

	max_pool
	       maximum size of free pool.

	max_age
	       max age of free element.

   pool_sess
	* Default: 10,100,10

     Parameters for per worker pool session memory pool.

     The three numbers are:

	min_pool
	       minimum size of free pool.

	max_pool
	       maximum size of free pool.

	max_age
	       max age of free element.

   pool_vbo
	* Default: 10,100,10

     Parameters for backend object fetch memory pool.

     The three numbers are:

	min_pool
	       minimum size of free pool.

	max_pool
	       maximum size of free pool.

	max_age
	       max age of free element.

   prefer_ipv6
	* Units: bool

	* Default: off

     Prefer  IPv6  address  when connecting to backends which have both IPv4 and
     IPv6 addresses.

   rush_exponent
	* Units: requests per request

	* Default: 3

	* Minimum: 1

	* Flags: experimental

     How many parked request we start for each completed request on the  object.
     NB:  Even	with  the implicit delay of delivery, this parameter controls an
     exponential increase in number of worker threads. A value of 1 will instead
     serialize requests resumption and is only useful for testing purposes.

   send_timeout
	* Units: seconds

	* Default: 600.000

	* Minimum: 0.000

	* Flags: timeout, delayed

     Total timeout for ordinary HTTP1 responses. Does not apply to  some  inter-
     nally generated errors and pipe mode.

     When  'idle_send_timeout' is hit while sending an HTTP1 response, the time-
     out is extended unless the total time already taken  for  sending	the  re-
     sponse in its entirety exceeds this many seconds.

     When this timeout is hit, the session is closed

   shortlived
	* Units: seconds

	* Default: 10.000

	* Minimum: 0.000

     Objects  created  with (ttl+grace+keep) shorter than this are always put in
     transient storage.

   sigsegv_handler
	* Units: bool

	* Default: on

	* Flags: must_restart

     Install a signal handler which tries to dump debug information on segmenta-
     tion faults, bus errors and abort signals.

   startup_timeout
	* Units: seconds

	* Default: 0.000

	* Minimum: 0.000

	* Flags: timeout

     Alternative timeout for the initial worker process startup.  If cli_timeout
     is longer than startup_timeout, it is used instead.

   syslog_cli_traffic
	* Units: bool

	* Default: on

     Log all CLI traffic to syslog(LOG_INFO).

   tcp_fastopen
     NB: This parameter depends on a feature which is not available on all plat-
     forms.

	* Units: bool

	* Default: off

	* Flags: must_restart

     Enable TCP Fast Open extension.

   tcp_keepalive_intvl
     NB: This parameter depends on a feature which is not available on all plat-
     forms.

	* Units: seconds

	* Default: platform dependent

	* Minimum: 1.000

	* Maximum: 100.000

	* Flags: experimental

     The number of seconds between TCP keep-alive probes. Ignored for  Unix  do-
     main sockets.

   tcp_keepalive_probes
     NB: This parameter depends on a feature which is not available on all plat-
     forms.

	* Units: probes

	* Default: platform dependent

	* Minimum: 1

	* Maximum: 100

	* Flags: experimental

     The  maximum  number  of TCP keep-alive probes to send before giving up and
     killing the connection if no response is obtained from the other  end.  Ig-
     nored for Unix domain sockets.

   tcp_keepalive_time
     NB: This parameter depends on a feature which is not available on all plat-
     forms.

	* Units: seconds

	* Default: platform dependent

	* Minimum: 1.000

	* Maximum: 7200.000

	* Flags: experimental

     The number of seconds a connection needs to be idle before TCP begins send-
     ing out keep-alive probes. Ignored for Unix domain sockets.

   thread_pool_add_delay
	* Units: seconds

	* Default: 0.000

	* Minimum: 0.000

	* Flags: experimental

     Wait at least this long after creating a thread.

     Some  (buggy)  systems may need a short (sub-second) delay between creating
     threads.  Set this to a few milliseconds if you  see  the	'threads_failed'
     counter grow too much.

     Setting this too high results in insufficient worker threads.

   thread_pool_destroy_delay
	* Units: seconds

	* Default: 1.000

	* Minimum: 0.010

	* Flags: delayed, experimental

     Wait this long after destroying a thread.

     This controls the decay of thread pools when idle(-ish).

   thread_pool_fail_delay
	* Units: seconds

	* Default: 0.200

	* Minimum: 0.010

	* Flags: experimental

     Wait  at  least  this  long after a failed thread creation before trying to
     create another thread.

     Failure to create a worker thread is often a sign that  the  end  is  near,
     because  the  process is running out of some resource.  This delay tries to
     not rush the end on needlessly.

     If thread creation failures are a problem, check  that  thread_pool_max  is
     not too high.

     It  may  also  help to increase thread_pool_timeout and thread_pool_min, to
     reduce the rate at which treads are destroyed and later recreated.

   thread_pool_max
	* Units: threads

	* Default: 5000

	* Minimum: thread_pool_min

	* Flags: delayed

     The maximum number of worker threads in each pool.

     Do not set this higher than you have to, since excess worker  threads  soak
     up RAM and CPU and generally just get in the way of getting work done.

   thread_pool_min
	* Units: threads

	* Default: 100

	* Minimum: 5

	* Maximum: thread_pool_max

	* Flags: delayed

     The minimum number of worker threads in each pool.

     Increasing  this  may  help ramp up faster from low load situations or when
     threads have expired.

     Technical minimum is 5 threads, but this parameter is strongly  recommended
     to be at least 10

   thread_pool_reserve
	* Units: threads

	* Default: 0 (auto-tune: 5% of thread_pool_min)

	* Maximum: 95% of thread_pool_min

	* Flags: delayed

     The number of worker threads reserved for vital tasks in each pool.

     Tasks may require other tasks to complete (for example, client requests may
     require backend requests, http2 sessions require streams, which require re-
     quests). This reserve is to ensure that lower priority tasks do not prevent
     higher priority tasks from running even under high load.

     The  effective  value  is	at  least  5  (the  number  of internal priority
     classes), irrespective of this parameter.

   thread_pool_stack
	* Units: bytes

	* Default: 80k

	* Minimum: sysconf(_SC_THREAD_STACK_MIN)

	* Flags: delayed

     Worker thread stack size.	This will likely be rounded up to a multiple  of
     4k (or whatever the page_size might be) by the kernel.

     The  required stack size is primarily driven by the depth of the call-tree.
     The most common relevant determining factors in Vinyl Cache core  code  are
     GZIP  (un)compression, ESI processing and regular expression matches. VMODs
     may also require significant amounts of additional stack. The nesting depth
     of VCL subs is another factor, although typically not predominant.

     The stack size is per thread, so the  maximum  total  memory  required  for
     worker   thread   stacks	is  in	the  order  of	size  =  thread_pools  x
     thread_pool_max x thread_pool_stack.

     Thus, in particular for setups with many threads, keeping the stack size at
     a minimum helps reduce the amount of memory required by Vinyl Cache.

     On the other hand, thread_pool_stack must be large enough under all circum-
     stances, otherwise Vinyl Cache will crash due to a stack overflow. Usually,
     a stack overflow manifests itself as a segmentation fault (aka  segfault  /
     SIGSEGV) with the faulting address being near the stack pointer (sp).

     Unless stack usage can be reduced, thread_pool_stack must be increased when
     a	stack overflow occurs. Setting it in 150%-200% increments is recommended
     until stack overflows cease to occur.

   thread_pool_timeout
	* Units: seconds

	* Default: 300.000

	* Minimum: 10.000

	* Flags: delayed, experimental

     Thread idle threshold.

     Threads in excess of thread_pool_min, which have been  idle  for  at  least
     this long, will be destroyed.

   thread_pool_watchdog
	* Units: seconds

	* Default: 60.000

	* Minimum: 0.100

	* Flags: experimental

     Thread queue stuck watchdog.

     If no queued work have been released for this long, the worker process pan-
     ics itself.

   thread_pools
	* Units: pools

	* Default: 2

	* Minimum: 1

	* Maximum: 32

	* Flags: delayed, experimental

     Number of worker thread pools.

     Increasing  the  number  of  worker  pools  decreases lock contention. Each
     worker pool also has a thread accepting new connections, so for  very  high
     rates  of	incoming  new connections on systems with many cores, increasing
     the worker pools may be required.

     Too many pools waste CPU and RAM resources, and more than one pool for each
     CPU is most likely detrimental to performance.

     Can be increased on the fly, but decreases require a restart  to  take  ef-
     fect, unless the drop_pools experimental debug flag is set.

   thread_queue_limit
	* Units: requests

	* Default: 20

	* Minimum: 0

	* Flags: experimental

     Permitted request queue length per thread-pool.

     This  sets  the  number of requests we will queue, waiting for an available
     thread.  Above this limit sessions will be dropped instead of queued.

   thread_stats_rate
	* Units: requests

	* Default: 10

	* Minimum: 0

	* Flags: experimental

     Worker threads accumulate statistics, and dump these into the global  stats
     counters  if  the	lock is free when they finish a job (request/fetch etc.)
     This parameters defines the maximum number of jobs a worker thread may han-
     dle, before it is forced to dump its  accumulated	stats  into  the  global
     counters.

   timeout_idle
	* Units: seconds

	* Default: 5.000

	* Minimum: 0.000

	* Maximum: 3600.000

     Idle timeout for client connections.

     A	connection  is	considered  idle until we have received the full request
     headers.

     This parameter is particularly relevant for  HTTP1  keepalive   connections
     which are closed unless the next request is received before this timeout is
     reached.

   timeout_linger
	* Units: seconds

	* Default: 0.050

	* Minimum: 0.000

	* Flags: experimental

     How  long	the  worker  thread lingers on an idle session before handing it
     over to the waiter.  When sessions are reused,  as  much  as  half  of  all
     reuses happen within the first 100 msec of the previous request completing.
     Setting  this  too  high  results	in worker threads not doing anything for
     their keep, setting it too low just means that more sessions take a  detour
     around the waiter.

   transit_buffer
	* Units: bytes

	* Default: 0b

	* Minimum: 0b

     The  number  of  bytes  which  Vinyl  Cache buffers for uncacheable backend
     streaming fetches - in other words, how many bytes Vinyl Cache  reads  from
     the  backend ahead of what has been sent to the client.  A zero value means
     no limit, the object is fetched as fast as possible.

     When dealing with slow clients, setting this parameter to non-zero can pre-
     vent large uncacheable objects from being stored in full when the intent is
     to simply stream them to the client. As a result, a slow client transaction
     holds onto a backend connection until the end of the delivery.

     This parameter is the default to the  VCL	variable  beresp.transit_buffer,
     which can be used to control the transit buffer per backend request.

   uncacheable_ttl
	* Units: seconds

	* Default: 2m

	* Minimum: 0.000

	* Flags: obj_sticky

     The TTL assigned to uncacheable objects by the built-in VCL.

   vary_notice
	* Units: variants

	* Default: 10

	* Minimum: 1

     How  many variants need to be evaluated to log a Notice that there might be
     too many variants.

   vcc_allow_inline_c
     Deprecated alias for the vcc_feature parameter.

   vcc_err_unref
     Deprecated alias for the vcc_feature parameter.

   vcc_feature
	* Default: none,+err_unref,+unsafe_path

     Enable/Disable various VCC behaviors.

	default
	       Set default value (deprecated: use param.reset)

	none   Disable all behaviors.

     Use +/- prefix to enable/disable individual behavior:

	err_unref
	       Unreferenced VCL objects result in error.

	allow_inline_c
	       Allow inline C code in VCL.

	unsafe_path
	       Allow '/' in vmod & include paths. Allow 'import ... from ...'.

   vcc_unsafe_path
     Deprecated alias for the vcc_feature parameter.

   vcl_cooldown
	* Units: seconds

	* Default: 600.000

	* Minimum: 1.000

     How long a VCL is kept warm after being replaced as the active VCL  (granu-
     larity approximately 30 seconds).

   vcl_path
     NB:  The actual default value for this parameter depends on the Vinyl Cache
     build environment and options.

	* Default: ${sysconfdir}/vinyl-cache:${datadir}/vinyl-cache/vcl

     Directory (or colon separated list of directories) from which relative  VCL
     filenames	(vcl.load  and include) are to be found.  By default Vinyl Cache
     searches VCL files in both the system configuration and shared data  direc-
     tories  to  allow	packages  to drop their VCL files in a standard location
     where relative includes would work. Includes using +glob cannot be searched
     in vcl_path.

   vmod_path
     NB: The actual default value for this parameter depends on the Vinyl  Cache
     build environment and options.

	* Default: ${libdir}/vinyl-cache/vmods

     Directory	(or  colon  separated list of directories) where VMODs are to be
     found.

   vsl_buffer
	* Units: bytes

	* Default: 16k

	* Minimum: vsl_reclen + 12 bytes

     Bytes of (req-/backend-)workspace dedicated to buffering VSL records.  When
     this  parameter  is  adjusted,  most  likely  workspace_client  and   work-
     space_backend will have to be adjusted by the same amount.

     Setting  this too high costs memory, setting it too low will cause more VSL
     flushes and likely increase lock-contention on the VSL mutex.

   vsl_mask
	* Default: all,-Debug,-ObjProtocol,-ObjStatus,-ObjReason,-ObjHeader,-Ex-
	  pKill,-WorkThread,-Hash,-VfpAcct,-H2RxHdr,-H2RxBody,-H2TxHdr,-H2Tx-
	  Body,-VdpAcct,-ReqTarget

     Mask individual VSL messages from being logged.

	all    Enable all tags

	default
	       Set default value (deprecated: use param.reset)

     Use +/- prefix in front of VSL tag name to unmask/mask individual VSL  mes-
     sages. See vsl(7) for possible values.

   vsl_reclen
	* Units: bytes

	* Default: 255b

	* Minimum: 16b

	* Maximum: vsl_buffer - 12 bytes

     Maximum number of bytes in SHM log record.

   vsl_space
	* Units: bytes

	* Default: 80M

	* Minimum: 1M

	* Maximum: 4G

	* Flags: must_restart

     The  amount  of space to allocate for the VSL fifo buffer in the VSM memory
     segment.  If you make this too small, vinyl{ncsa|log} etc will not be  able
     to keep up.  Making it too large just costs memory resources.

   vsm_free_cooldown
	* Units: seconds

	* Default: 60.000

	* Minimum: 10.000

	* Maximum: 600.000

     How long VSM memory is kept warm after a deallocation (granularity approxi-
     mately 2 seconds).

   workspace_backend
	* Units: bytes

	* Default: 96k

	* Minimum: 1k

	* Flags: delayed

     Bytes of HTTP protocol workspace for backend HTTP req/resp.  If larger than
     4k, use a multiple of 4k for VM efficiency.

   workspace_client
	* Units: bytes

	* Default: 96k

	* Minimum: 9k

	* Flags: delayed

     Bytes of HTTP protocol workspace for clients HTTP req/resp.  Use a multiple
     of  4k for VM efficiency.	For HTTP/2 compliance this must be at least 20k,
     in order to receive fullsize (=16k) frames from the client.   That  usually
     happens only in POST/PUT bodies.  For other traffic-patterns smaller values
     work just fine.

   workspace_session
	* Units: bytes

	* Default: 0.75k

	* Minimum: 384b

	* Flags: delayed

     Allocation  size  for  session structure and workspace.	The workspace is
     primarily used for TCP connection addresses.  If larger than 4k, use a mul-
     tiple of 4k for VM efficiency.

   workspace_thread
	* Units: bytes

	* Default: 2k

	* Minimum: 0.25k

	* Maximum: 8k

	* Flags: delayed

     Bytes of auxiliary workspace per thread.  This workspace is used  for  cer-
     tain  temporary  data  structures	during the operation of a worker thread.
     One use is for the IO-vectors used during delivery. Setting this  parameter
     too  low  may increase the number of writev() syscalls, setting it too high
     just wastes space.  ~0.1k + UIO_MAXIOV * sizeof(struct iovec) (typically  =
     ~16k  for	64bit)	is considered the maximum sensible value under any known
     circumstances (excluding exotic vmod use).

EXIT CODES
     Vinyl Cache and bundled tools will, in most cases, exit  with  one  of  the
     following codes

     * 0 OK

     * 1 Some error which could be system-dependent and/or transient

     * 2  Serious  configuration / parameter error - retrying with the same con-
       figuration / parameters is most likely useless

     The vinyld master process may also OR its exit code

     * with 0x20 when the vinyld child process died,

     * with 0x40 when the vinyld child process was terminated by a signal and

     * with 0x80 when a core was dumped.

SEE ALSO
     * vinyllog(1)

     * vinylhist(1)

     * vinylncsa(1)

     * vinylstat(1)

     * vinyltop(1)

     * vinyl-cli(7)

     * vcl(7)

HISTORY
     The vinyld daemon was developed by Poul-Henning Kamp  in  cooperation  with
     Verdens Gang AS and Redpill-Linpro

     This  manual  page was written by Dag-Erling SmA,rgrav with updates by Stig
     Sandbeck Mathisen < <ssm@debian.org> >, Nils Goroll and others.

COPYRIGHT
     This document is licensed under the same licence as Vinyl Cache itself. See
     LICENCE for details.

     * Copyright (c) 2007-2015 Varnish Software AS

								       VINYLD(1)

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