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I have to deal with mod_cluster, and it is extremely memory hungry (in the GB range per process). As mitigation, I’m trying to get down to a single apache worker process per host when we aren’t under heavy load. That would save me
about 6GB per host. We have several hosts running the exact same thing behind a load balancer and I’ve never seen a crash, so I’m not concerned with running a single instance. Running 4 20 thread instances is almost 4 times the memory of this one instance,
for example. This is the relevant portion of the configuration: LoadModule mpm_event_module modules/mod_mpm_event.so ServerLimit 8 StartServers 1 ThreadLimit 80 ThreadsPerChild 80 MaxRequestWorkers 640 MaxSpareThreads 120 MinSpareThreads 8 The top of mod-Status: Apache Server Status for HOSTNAME (via 10.X.X.X) Server Version: CUSTOMSTRING/2.4.18 (Unix) OpenSSL/1.0.1e-fips mod_cluster/1.3.1.Final Server MPM: event Server Built: Dec 16 2015 16:07:29 ________________________________________ Current Time: Tuesday, 17-May-2016 14:37:00 EDT Restart Time: Monday, 02-May-2016 09:36:16 EDT Parent Server Config. Generation: 10 Parent Server MPM Generation: 9 Server uptime: 15 days 5 hours 44 seconds Server load: 0.72 0.75 0.89 Total accesses: 39007867 - Total Traffic: 1.7 GB CPU Usage: u2533.2 s168.49 cu0 cs0 - .206% CPU load 29.7 requests/sec - 1364 B/second - 45 B/request 5 requests currently being processed, 155 idle workers PID Connections Threads Async connections total accepting busy idle writing keep-alive closing
11397 35 yes 2 78 0 33 0
29323 26 yes 3 77 0 23 0
Sum 61 5 155 0 56 0
................................................................ ................________________________________________________ _______W____W___________________................................ ................................................____________W___ ______W__________________________________W______________________ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ The idle threads here usually stays around the mid 150s. These particular workers were started about 40 minutes apart, but I have the similar pattern showing in other regions with similar start times and the same workers being up for
over a month. Given the MaxSpareThreads 120, I would expect this to drop the second worker fairly quickly and work as described (https://httpd.apache.org/docs/2.4/mod/mpm_common.html#maxsparethreads).
But, that’s not happening and I'm stuck with two processes handling the load. It's acting almost as if there is a "ServerMin 2" directive hard-coded or something. This certainly looks like a bug (whether in the documentation or the code itself). Any suggestions on how to get this to work before I submit a bug ticket? Thank you, Rick Houser |
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