There are numerous reports of Apache HTTPD looping forever on Windows unless the LDAPSharedCacheSize option is set to zero.
See for instance: https://svn.haxx.se/users/archive-2014-05/0000.shtml https://subversion.open.collab.net/ds/viewMessage.do?dsMessageId=564176&dsForumId=3 https://subversion.open.collab.net/ds/viewMessage.do?dsForumId=3&viewType=browseAll&dsMessageId=539507 https://stackoverflow.com/questions/44542654/collabnet-subversion-server-reaching-cpu-100-because-of-httpd-exe-process I looked around for a while but don't know yet if a corresponding issue in the HTTPD bug tracker exists. Does anyone know? On the surface it looks like a memory pool corruption bug to me. The stack trace posted in https://svn.haxx.se/users/archive-2014-05/0000.shtml points towards an endless loop in apr_pool_cleanup_kill(). The trace ends at APR-util's misc/apr_reslist.c:apr_reslist_cleanup_order_set, and of the functions this calls only apr_pool_cleanup_kill() contains loops. I could not do any further debugging since I only had a production setup to look at, which is stable with the workaround 'LDAPSharedCacheSize 0'. I also do not have a Windows dev environment and I don't plan on digging any further. Until the real bug gets found and fixed, I would recommend making the known workaround the default on Windows. Because the winnt MPM runs a single process, there is no benefit to a shared memory cache anyway. Should I commit this patch? Index: modules/ldap/util_ldap.c =================================================================== --- modules/ldap/util_ldap.c (revision 1803972) +++ modules/ldap/util_ldap.c (working copy) @@ -2815,7 +2815,17 @@ static void *util_ldap_create_config(apr_pool_t *p apr_thread_mutex_create(&st->mutex, APR_THREAD_MUTEX_DEFAULT, st->pool); #endif +#ifdef WIN32 + /* XXX The shared memory cache can cause an endless loop on Windows. + * See https://svn.haxx.se/users/archive-2014-05/0000.shtml and + * similar reports elsewhere which recommend 'LDAPSharedCacheSize 0' + * as a workaround. + * Because the winnt MPM uses a single process a shared cache is + * not needed anyway so leave it disabled by default. */ + st->cache_bytes = 0; +#else st->cache_bytes = 500000; +#endif st->search_cache_ttl = 600000000; st->search_cache_size = 1024; st->compare_cache_ttl = 600000000;
