>Number: 4316
>Category: mod_proxy
>Synopsis: proposed fix for excessive forking in proxy_cache.c for
>garbage collection (see #3161 and #3202)
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: apache
>State: open
>Class: sw-bug
>Submitter-Id: apache
>Arrival-Date: Tue Apr 27 11:50:00 PDT 1999
>Last-Modified:
>Originator: [EMAIL PROTECTED]
>Organization:
apache
>Release: 1.3.6
>Environment:
SunOS 5.6 Generic_105181-08 sun4u sparc SUNW,Ultra-Enterprise
Apache 1.3.6
>Description:
For environments other than WIN32 / OS2 / MPE, proxy_cache uses
detached_proxy_garbage_coll, which forks (twice) prior to calling
help_proxy_garbage_coll, which determines if garbage collection should be done.
This results in two extra processes being created and killed for each request
through the proxy.
The suggested fix checks if garbage collection should be done prior to forking.
-----
Note... I'm wondering about the use of the request_rec in garbage collection
when detached_proxy_garbage_coll is used. Specifically, I see that ap_palloc
is called to allocate memory after the double fork. I'm guessing that the
memory will be released when the grandparent exits and could result in
problems during garbage collection. I'm going to do some tests to see if this
is in fact true.
>How-To-Repeat:
>Fix:
Diff of changes to proxy_cache.c:
108a109,110
> /* 4/26/99 lastcheck moved to file scope for use in
> detached_proxy_garbage_coll */
> static time_t lastcheck = BAD_DATE; /* static (per-process) data!!!
> */
200a203
>
207a211,245
> /* 4/26/99 added: make Garbage Collection time checks prior to forking */
>
> void *sconf = r->server->module_config;
> proxy_server_conf *pconf =
> (proxy_server_conf *) ap_get_module_config(sconf, &proxy_module);
> const struct cache_conf *conf = &pconf->cache;
> const char *cachedir;
> struct stat buf;
>
> cachedir = conf->root;
> every = conf->gcinterval;
>
> if ((conf->root == NULL) || (every == -1))
> return;
>
> garbage_now = time(NULL);
>
> /* If we don't have a garbage collection time, get the cache's timestamp */
>
> if (lastcheck == BAD_DATE) {
> filename = ap_palloc(r->pool, strlen(cachedir) + 7);
> strcpy(filename, cachedir);
> strcat(filename, "/.time");
> if (stat(filename, &buf) != -1) {
> lastcheck = buf.st_mtime;
> }
> }
>
> if (garbage_now != -1 && lastcheck != BAD_DATE && garbage_now < lastcheck
> + every)
> return;
>
> /* Reset lastcheck to force obtaining timestamp next time through */
>
> lastcheck = BAD_DATE;
>
249a288
>
278d316
< static time_t lastcheck = BAD_DATE; /* static (per-process)
data!!! */
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