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Posted to bugs@httpd.apache.org by bu...@apache.org on 2015/06/03 02:42:35 UTC

[Bug 53555] Scoreboard full error with event/ssl

https://bz.apache.org/bugzilla/show_bug.cgi?id=53555

--- Comment #12 from lscotte@gmail.com ---
After migrating from worker MPM to event MPM with Apache 2.4.7 we are seeing
this same problem.

Server version: Apache/2.4.7 (Ubuntu)
Ubuntu Trusty 14.04.2 LTS
Linux 3.13.0-40-generic #69-Ubuntu SMP Thu Nov 13 17:53:56 UTC 2014 x86_64
x86_64 x86_64 GNU/Linux

We explicitly moved to event MPM for this workload, which is a proxy of
thousands of mostly-idle HTTP Keep-Alive connections - since event MPM doesn't
require a thread per Keep-Alive connection. Although our number of clients is
fairly consistent, and we have MaxConnectionsPerChild=0, we observe Apache
processes going into GGGGGG state until eventually Apache no longer accepts
connections.

If we set MinSpareThreads and MaxSpareThreads equal to MaxRequestWorkers (so
Apache doesn't attempt to scale down processes), the issue goes away (as
expected, but validates (maybe?) this has to do with Apache scale-down).

Since client connections can be connected for hours or days, Apache processes
stay in this state for a very long time, eventually rejecting client
connections and becoming wedged.

Our clients are not browsers - Apache is being used for a mid-tier load
balancer/proxy with client connections that are very long lived (long
Keep-Alive times).

248 requests/sec - 0.7 MB/second - 3114 B/request
2 requests currently being processed, 38 idle workers
PID    Connections    Threads    Async connections
total    accepting    busy    idle    writing    keep-alive    closing
28483    1642    no    0    0    0    1642    0
29672    553    yes    1    19    0    552    0
29696    9    no    0    0    0    9    0
29588    173    no    0    0    0    173    0
29618    1    no    0    0    0    1    0
29644    6    no    0    0    0    6    0
29719    30    no    0    0    0    30    0
29743    237    yes    1    19    0    236    0
Sum    2651         2    38    0    2649    0
GGGGGGGGGGGGGGGGGGGG________W___________GGGGGGGGGGGGGGGGGGGGGGWG
GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG
GGGGGGGGGGGG________W___________................................
........

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