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Make helper queue size configurable, with consistent defaults and bet…
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…ter overflow handling.

This patch adds a queue-size=N option to helpers configuration. This
option allows users to configure the maximum number of queued requests
to busy helpers. We also adjusted the default queue size limits to be
more consistent across all helpers and made Squid more robust on some
queue overflows:

- external_acl helpers
    Make the maximum queue size configurable via queue-size.
    Default to 2*maximum-number-of-children.
    If the queue overflows, then the ACL returns ACCESS_DUNNO.

    Unpatched code uses the number of running children as the maximum
    queue size. If the queue is overloaded, then the ACL returns ACCESS_DUNNO.

-redirector/storeID helpers
    Make the maximum queue size configurable via queue-size.
    Default to 2*maximum-number-of-children.
    If the queue overflows and redirector_bypass configuration option
    is set, then redirector is bypassed. Otherwise, if overloading
    persists for more than 3 minutes squid quits with a FATAL message.
    If the redirector_bypass/storeID_bypass is set then the default queue_size
    is set to 0 for backward compatibility.

    Unpatched code uses 2*number-of-running-children as the maximum queue size.
    If the redirector_bypass/storeID_bypass is set then helper bypassed if all
    of the children are busy.
    If the queue is overloaded and redirector_bypass/storeID_bypass is not set
    then squid quits with a FATAL message.

- ssl_crtd/ssl_crtd_validator helpers.
    Make the maximum queue size configurable via queue-size.
    Default to 2*maximum-number-of-children.
    If the queue overflows, then helpers are bypassed. If overloading persists
    for more than 3 minutes squid quits with a FATAL message.

    The default size limit and overflow behavior has not changed.

- Authentication helpers
    Make the maximum queue size configurable via queue-size.
    Default to 2*maximum-number-of-children.
    If the queue overflows and overloading persists for more than 3 minutes,
    then squid quits with a FATAL message.

    The default size limit and overflow behavior has not changed.

This is a Measurement Factory project
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@chtsanti
chtsanti committed Nov 9, 2014
1 parent a6950c2 commit 6825b10
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31 changes: 26 additions & 5 deletions doc/release-notes/release-3.6.html
View file
Expand Up @@ -24,7 +24,7 @@ <H2><A NAME="toc1">1.</A> <A HREF="#s1">Notice</A></H2>
<H2><A NAME="toc2">2.</A> <A HREF="#s2">Major new features since Squid-3.5</A></H2>

<UL>
<LI><A NAME="toc2.1">2.1</A> <A HREF="#ss2.1">BLAH</A>
<LI><A NAME="toc2.1">2.1</A> <A HREF="#ss2.1">Configurable helper queue size</A>
</UL>
<P>
<H2><A NAME="toc3">3.</A> <A HREF="#s3">Changes to squid.conf since Squid-3.5</A></H2>
Expand Down Expand Up @@ -91,12 +91,11 @@ <H2><A NAME="s2">2.</A> <A HREF="#toc2">Major new features since Squid-3.5</A></
<P>Most user-facing changes are reflected in squid.conf (see below).</P>


<H2><A NAME="ss2.1">2.1</A> <A HREF="#toc2.1">BLAH</A>
<H2><A NAME="ss2.1">2.1</A> <A HREF="#toc2.1">Configurable helper queue size</A>
</H2>

<P>Details at
<A HREF="http://wiki.squid-cache.org/Features/BLAH">http://wiki.squid-cache.org/Features/BLAH</A>.</P>

<P>The new queue-size=N option to helpers configuration, allows users
to configure the maximum number of queued requests to busy helpers.</P>

<H2><A NAME="s3">3.</A> <A HREF="#toc3">Changes to squid.conf since Squid-3.5</A></H2>

Expand Down Expand Up @@ -128,7 +127,29 @@ <H2><A NAME="modifiedtags"></A> <A NAME="ss3.2">3.2</A> <A HREF="#toc3.2">Change

<P>
<DL>
<DT><B> auth_param </B><DD>
<P> New parameter <EM>queue-size=</EM> to set the maximum number
of queued requests.</P>

<DT><B>external_acl_type</B><DD>

<DT><B></B><DD>
<P> New parameter <EM>queue-size=</EM> to set the maximum number
of queued requests.</P>

<DT><B>url_rewrite_children</B><DD>

<DT><B></B><DD>
<P> New parameter <EM>queue-size=</EM> to set the maximum number
of queued requests.</P>

<DT><B>sslcrtd_children</B><DD>
<P> New parameter <EM>queue-size=</EM> to set the maximum number
of queued requests.</P>

<DT><B>sslcrtvalidator_children</B><DD>
<P> New parameter <EM>queue-size=</EM> to set the maximum number
of queued requests.</P>
</DL>
</P>

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24 changes: 21 additions & 3 deletions doc/release-notes/release-3.6.sgml
View file
Expand Up @@ -44,9 +44,9 @@ The 3.6 change history can be <url url="http://www.squid-cache.org/Versions/v3/3
Most user-facing changes are reflected in squid.conf (see below).


<sect1>BLAH
<p>Details at <url url="http://wiki.squid-cache.org/Features/BLAH">.

<sect1>Configurable helper queue size
<p>The new queue-size=N option to helpers configuration, allows users
to configure the maximum number of queued requests to busy helpers.

<sect>Changes to squid.conf since Squid-3.5
<p>
Expand All @@ -70,7 +70,25 @@ This section gives a thorough account of those changes in three categories:
<sect1>Changes to existing tags<label id="modifiedtags">
<p>
<descrip>
<tag> auth_param </tag>
<p> New parameter <em>queue-size=</em> to set the maximum number
of queued requests.

<tag>external_acl_type<tag>
<p> New parameter <em>queue-size=</em> to set the maximum number
of queued requests.

<tag>url_rewrite_children<tag>
<p> New parameter <em>queue-size=</em> to set the maximum number
of queued requests.

<tag>sslcrtd_children</tag>
<p> New parameter <em>queue-size=</em> to set the maximum number
of queued requests.

<tag>sslcrtvalidator_children</tag>
<p> New parameter <em>queue-size=</em> to set the maximum number
of queued requests.
</descrip>

<sect1>Removed tags<label id="removedtags">
Expand Down
45 changes: 44 additions & 1 deletion src/cf.data.pre
View file
Expand Up @@ -428,7 +428,7 @@ DOC_START
For Digest there is no default, this parameter is mandatory.
For NTLM and Negotiate this parameter is ignored.

"children" numberofchildren [startup=N] [idle=N] [concurrency=N]
"children" numberofchildren [startup=N] [idle=N] [concurrency=N] [queue-size=N]

The maximum number of authenticator processes to spawn. If
you start too few Squid will have to wait for them to process
Expand All @@ -453,6 +453,11 @@ DOC_START
Concurrency must not be set unless it's known the helper
supports the input format with channel-ID fields.

The queue-size= option sets the maximum number of queued
requests. If the queued requests exceed queue size for more
than 3 minutes then squid aborts its operation.
The default value is set to 2*numberofchildren/

NOTE: NTLM and Negotiate schemes do not support concurrency
in the Squid code module even though some helpers can.

Expand Down Expand Up @@ -646,6 +651,10 @@ DOC_START
Up to the value of children-max. (default 1)
concurrency=n concurrency level per process. Only used with helpers
capable of processing more than one query at a time.
queue-size=N The queue-size= option sets the maximum number of queued
requests. If the queued requests exceed queue size
the acl ignored.
The default value is set to 2*children-max.
cache=n limit the result cache size, default is 262144.
grace=n Percentage remaining of TTL where a refresh of a
cached entry should be initiated without needing to
Expand Down Expand Up @@ -2805,6 +2814,13 @@ DOC_START
at all times. When traffic begins to rise above what the existing
processes can handle this many more will be spawned up to the maximum
configured. A minimum setting of 1 is required.

queue-size=N

Sets the maximum number of queued requests.
If the queued requests exceed queue size for more than 3 minutes
squid aborts its operation.
The default value is set to 2*numberofchildren.

You must have at least one ssl_crtd process.
DOC_END
Expand Down Expand Up @@ -2864,6 +2880,13 @@ DOC_START
a request ID in front of the request/response. The request
ID from the request must be echoed back with the response
to that request.

queue-size=N

Sets the maximum number of queued requests.
If the queued requests exceed queue size for more than 3 minutes
squid aborts its operation.
The default value is set to 2*numberofchildren.

You must have at least one ssl_crt_validator process.
DOC_END
Expand Down Expand Up @@ -4869,6 +4892,14 @@ DOC_START
used to communicate with the helper is modified to include
an ID in front of the request/response. The ID from the request
must be echoed back with the response to that request.

queue-size=N

Sets the maximum number of queued requests.
If the queued requests exceed queue size and redirector_bypass
configuration option is set, then redirector is bypassed. Otherwise, if
overloading persists squid may abort its operation.
The default value is set to 2*numberofchildren.
DOC_END

NAME: url_rewrite_host_header redirect_rewrites_host_header
Expand Down Expand Up @@ -4919,6 +4950,8 @@ DOC_START
redirectors for access control, and you enable this option,
users may have access to pages they should not
be allowed to request.
This options sets default queue-size option of the url_rewrite_children
to 0.
DOC_END

NAME: url_rewrite_extras
Expand Down Expand Up @@ -5043,6 +5076,14 @@ DOC_START
used to communicate with the helper is modified to include
an ID in front of the request/response. The ID from the request
must be echoed back with the response to that request.

queue-size=N

Sets the maximum number of queued requests.
If the queued requests exceed queue size and store_id_bypass
configuration option is set, then storeID helper is bypassed. Otherwise,
if overloading persists squid may abort its operation.
The default value is set to 2*numberofchildren.
DOC_END

NAME: store_id_access storeurl_rewrite_access
Expand Down Expand Up @@ -5072,6 +5113,8 @@ DOC_START
are not critical to your caching system. If you use
helpers for critical caching components, and you enable this
option, users may not get objects from cache.
This options sets default queue-size option of the store_id_children
to 0.
DOC_END

COMMENT_START
Expand Down
25 changes: 13 additions & 12 deletions src/external_acl.cc
View file
Expand Up @@ -268,6 +268,9 @@ parse_externalAclHelper(external_acl ** list)
a->children.n_idle = atoi(token + 14);
} else if (strncmp(token, "concurrency=", 12) == 0) {
a->children.concurrency = atoi(token + 12);
} else if (strncmp(token, "queue-size=", 11) == 0) {
a->children.queue_size = atoi(token + 11);
a->children.defaultQueueSize = false;
} else if (strncmp(token, "cache=", 6) == 0) {
a->cache_size = atoi(token + 6);
} else if (strncmp(token, "grace=", 6) == 0) {
Expand Down Expand Up @@ -315,6 +318,9 @@ parse_externalAclHelper(external_acl ** list)
if (a->negative_ttl == -1)
a->negative_ttl = a->ttl;

if (a->children.queue_size < 0)
a->children.queue_size = 2 * a->children.n_max;

/* Parse format */
external_acl_format::Pointer *p = &a->format;

Expand Down Expand Up @@ -776,7 +782,7 @@ aclMatchExternal(external_acl_data *acl, ACLFilledChecklist *ch)
if (!entry) {
debugs(82, 2, HERE << acl->def->name << "(\"" << key << "\") = lookup needed");

if (acl->def->theHelper->stats.queue_size < (int)acl->def->theHelper->childs.n_active) {
if (!acl->def->theHelper->queueFull()) {
debugs(82, 2, HERE << "\"" << key << "\": queueing a call.");
if (!ch->goAsync(ExternalACLLookup::Instance()))
debugs(82, 2, "\"" << key << "\": no async support!");
Expand Down Expand Up @@ -1415,24 +1421,19 @@ ExternalACLLookup::Start(ACLChecklist *checklist, external_acl_data *acl, bool i
} else {
/* No pending lookup found. Sumbit to helper */

/* Check for queue overload */

if (def->theHelper->stats.queue_size >= (int)def->theHelper->childs.n_running) {
debugs(82, 7, HERE << "'" << def->name << "' queue is too long");
assert(inBackground); // or the caller should have checked
cbdataFree(state);
return;
}

/* Send it off to the helper */
MemBuf buf;
buf.init();

buf.Printf("%s\n", key);

debugs(82, 4, "externalAclLookup: looking up for '" << key << "' in '" << def->name << "'.");

helperSubmit(def->theHelper, buf.buf, externalAclHandleReply, state);
if (!def->theHelper->trySubmit(buf.buf, externalAclHandleReply, state)) {
debugs(82, 7, HERE << "'" << def->name << "' submit to helper failed");
assert(inBackground); // or the caller should have checked
cbdataFree(state);
return;
}

dlinkAdd(state, &state->list, &def->queue);

Expand Down

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