Merge r1696105, r1700418 from trunk:

With the current implementation, it is likely to connect/close a socket with the memcache server for each command sent.
The root cause is a too small idle timeout (600 microseconds).

Add a new directive, 'MemcacheConnTTL',  to control this idle connection timeout with the memcache server(s).
Change the default value from 600 usec (!) to 15 sec as per Yann suggestion.

I've limited accepted values from 1 to 1800 seconds (half an hour) because internaly, the value passed to 'apr_memcache_server_create' is still in mirco-seconds.

PR 58091
~~~~~~~~~~~~~~~~~~~_
Homemade measurement (on a slighly modified version of httpd) shows a +30% in number of processed requests using memcache to cache /index.html.
Comparison made between the 600 usec and 15 sec TTL.

Memcache config:
    default
httpd Config:
    CacheEnable socache /
    CacheSocache memcache:127.0.0.1
    LoadModule mpm_event_module modules/mod_mpm_event.so
httpd compiled with:
    ./configure --enable-mpms-shared=all --with-included-apr --with-mysql --with-libxml2 --enable-modules=reallyall --enable-ssl-ct=no --enable-maintainer-mode --prefix=$HOME/httpd-2.5
httpd and memcache running on the same VM running under Ubuntu 15.04
Load tested using:
    ab -n 20000 http://127.0.0.1/index.html

Creation/closing of connections beetween httpd and memcache confirmed using the telnet connection to memcache and the stats command

Allow 0 as a valid value (never close idle connections)
Increased maximum allowed value to 3600 s (1 hour)
Use 'ap_timeout_parameter_parse' to allow more flexible configuration (i.e. h, min, s, ms suffixes)
Use 'apr_time_from_sec' when applicable.
Submitted by: jailletc36
Reviewed/backported by: jim

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1701771 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/CHANGES b/CHANGES
index bbe52e8419e07ec05671b5760deea801c3db654c..b669af72b47d83f09756acfe50caf6c14ef5a3c8 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -15,6 +15,11 @@ Changes with Apache 2.4.17
   *) mod_authz_dbd: Avoid a crash when lacking correct DB access permissions.
      PR 57868. [Jose Kahan <jose w3.org>, Yann Ylavic]
 
+  *) mod_socache_memcache: Add the 'MemcacheConnTTL' directive to control how 
+     long to keep idle connections with the memcache server(s).
+     Change default value from 600 usec (!) to 15 sec. PR 58091
+     [Christophe Jaillet]
+
   *) mod_dir: Prevent the internal identifier "httpd/unix-directory" from
      appearing as a Content-Type response header when requests for a directory
      are rewritten by mod_rewrite. [Eric Covener]

diff --git a/STATUS b/STATUS
index 6e12fad9a44d04dcb3c0a5d8e9e96ab821673506..58e436e7563cff206fbc79b0dd59a0f44a6be690 100644 (file)
--- a/STATUS
+++ b/STATUS
@@ -109,18 +109,6 @@ RELEASE SHOWSTOPPERS:
 PATCHES ACCEPTED TO BACKPORT FROM TRUNK:
   [ start all new proposals below, under PATCHES PROPOSED. ]
 
-  *) mod_socache_memcache: Add the 'MemcacheConnTTL' directive to control how 
-     long to keep idle connections with the memcache server(s).
-     Change default value from 600 usec (!) to 15 sec.  PR 58091
-     Measurements available in the svn commit message.
-     trunk: http://svn.apache.org/r1696105
-            http://svn.apache.org/r1700418
-     2.4.x: http://people.apache.org/~jailletc36/socache_memcache.diff
-     +1: jailletc36, ylavic, covener
-     covener: please add compatibility tag to doc during backport
-     jailletc36: done in r1700418
-
-
   *) Fix some spurious and/or inconsistant indent spotted by sparse
      Fix some minor style issues.
      trunk: http://svn.apache.org/r1700317

diff --git a/docs/manual/mod/mod_socache_memcache.xml b/docs/manual/mod/mod_socache_memcache.xml
index a25a39be91129b664292f99601e4051434fabc19..5bf4dfee6ce4104fed571c83df418fc7a1ef14ec 100644 (file)
--- a/docs/manual/mod/mod_socache_memcache.xml
+++ b/docs/manual/mod/mod_socache_memcache.xml
@@ -52,4 +52,43 @@
 
 </summary>
 
+<directivesynopsis>
+<name>MemcacheConnTTL</name>
+<description>Keepalive time for idle connections</description>
+<syntax>MemcacheConnTTL <em>num[units]</em></syntax>
+<default>MemcacheConnTTL 15s</default>
+<contextlist>
+<context>server config</context>
+<context>virtual host</context>
+</contextlist>
+<compatibility>Available in Apache 2.4.17 and later</compatibility>
+
+<usage>
+
+    <p>Set the time to keep idle connections with the memcache server(s)
+    alive (threaded platforms only).</p>
+    
+    <p>Valid values for <directive>MemcacheConnTTL</directive> are times
+    up to one hour. 0 means no timeout.</p>
+
+    <note><p>This timeout defaults to units of seconds, but accepts
+    suffixes for milliseconds (ms), seconds (s), minutes (min), and hours (h).
+    </p></note>
+
+    <p>Before Apache 2.4.17, this timeout was hardcoded and its value was 600 usec.
+    So, the closest configuration to match the legacy behaviour is to set
+    <directive>MemcacheConnTTL</directive> to 1ms.</p>
+
+    <example>
+    <highlight language="config">
+# Set a timeout of 10 minutes
+MemcacheConnTTL 10min
+# Set a timeout of 60 seconds
+MemcacheConnTTL 60
+    </highlight>
+    </example>
+
+</usage>
+</directivesynopsis>
+
 </modulesynopsis>

diff --git a/modules/cache/mod_socache_memcache.c b/modules/cache/mod_socache_memcache.c
index 8cabd8a50ba7b3dcf58e8ff5dc28f044dceefeb8..e1fb2357bc94973725f92cf5d57e0d5ab9389718 100644 (file)
--- a/modules/cache/mod_socache_memcache.c
+++ b/modules/cache/mod_socache_memcache.c
@@ -51,9 +51,15 @@
 #endif
 
 #ifndef MC_DEFAULT_SERVER_TTL
-#define MC_DEFAULT_SERVER_TTL 600
+#define MC_DEFAULT_SERVER_TTL    apr_time_from_sec(15)
 #endif
 
+module AP_MODULE_DECLARE_DATA socache_memcache_module;
+
+typedef struct {
+    apr_uint32_t ttl;
+} socache_mc_svr_cfg;
+
 struct ap_socache_instance_t {
     const char *servers;
     apr_memcache_t *mc;
@@ -90,6 +96,9 @@ static apr_status_t socache_mc_init(ap_socache_instance_t *ctx,
     char *split;
     char *tok;
 
+    socache_mc_svr_cfg *sconf = ap_get_module_config(s->module_config,
+                                                     &socache_memcache_module);
+
     ap_mpm_query(AP_MPMQ_HARD_LIMIT_THREADS, &thread_limit);
 
     /* Find all the servers in the first run to get a total count */
@@ -140,7 +149,7 @@ static apr_status_t socache_mc_init(ap_socache_instance_t *ctx,
                                         MC_DEFAULT_SERVER_MIN,
                                         MC_DEFAULT_SERVER_SMAX,
                                         thread_limit,
-                                        MC_DEFAULT_SERVER_TTL,
+                                        sconf->ttl,
                                         &st);
         if (rv != APR_SUCCESS) {
             ap_log_error(APLOG_MARK, APLOG_CRIT, rv, s, APLOGNO(00788)
@@ -304,6 +313,38 @@ static const ap_socache_provider_t socache_mc = {
 
 #endif /* HAVE_APU_MEMCACHE */
 
+static void *create_server_config(apr_pool_t *p, server_rec *s)
+{
+    socache_mc_svr_cfg *sconf = apr_pcalloc(p, sizeof(socache_mc_svr_cfg));
+    
+    sconf->ttl = MC_DEFAULT_SERVER_TTL;
+
+    return sconf;
+}
+
+static const char *socache_mc_set_ttl(cmd_parms *cmd, void *dummy,
+                                      const char *arg)
+{
+    apr_interval_time_t ttl;
+    socache_mc_svr_cfg *sconf = ap_get_module_config(cmd->server->module_config,
+                                                     &socache_memcache_module);
+
+    if (ap_timeout_parameter_parse(arg, &ttl, "s") != APR_SUCCESS) {
+        return apr_pstrcat(cmd->pool, cmd->cmd->name,
+                           " has wrong format", NULL);
+    }
+
+    if ((ttl < apr_time_from_sec(0)) || (ttl > apr_time_from_sec(3600))) {
+        return apr_pstrcat(cmd->pool, cmd->cmd->name,
+                           " can only be 0 or up to one hour.", NULL);
+    }
+
+    /* apr_memcache_server_create needs a ttl in usec. */
+    sconf->ttl = ttl;
+
+    return NULL;
+}
+
 static void register_hooks(apr_pool_t *p)
 {
 #ifdef HAVE_APU_MEMCACHE
@@ -313,8 +354,18 @@ static void register_hooks(apr_pool_t *p)
 #endif
 }
 
+static const command_rec socache_memcache_cmds[] = {
+    AP_INIT_TAKE1("MemcacheConnTTL", socache_mc_set_ttl, NULL, RSRC_CONF,
+                  "TTL used for the connection with the memcache server(s)"),
+    { NULL }
+};
+
 AP_DECLARE_MODULE(socache_memcache) = {
     STANDARD20_MODULE_STUFF,
-    NULL, NULL, NULL, NULL, NULL,
-    register_hooks
+    NULL,                     /* create per-dir    config structures */
+    NULL,                     /* merge  per-dir    config structures */
+    create_server_config,     /* create per-server config structures */
+    NULL,                     /* merge  per-server config structures */
+    socache_memcache_cmds,    /* table of config file commands       */
+    register_hooks            /* register hooks                      */
 };