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Posted to users@httpd.apache.org by ho...@post.cz on 2020/04/29 17:54:12 UTC
[users@httpd] 2.4.37 (CentOS 8): event MPM: child process blocked out with Async connections stuck in the closing state
Hello,
we've been performing some load tests (using Apache JMeter) and noticed that
one HTTP Server child process become effectively blocked out (accepting =
no) with 67 Async connections stuck in the closing state (see the server
status output below).
It's been like that for several hours already and hasn't cleared yet (I
intentionally left it in that state to see if it would eventually clear
out). At the OS level there are no TCP connections (to this web server)
visible at all, everything has been fully closed.
Does anyone have any idea what may cause that - whether it's a HTTP Server
bug or some weird misconfiguration issue?
OS is CentOS 8 fully updated, with httpd installed from the standard
repository.
Server status:
Server Version: Apache/2.4.37 (centos)
Server MPM: event
Server Built: Dec 23 2019 20:45:34
Current Time: Wednesday, 29-Apr-2020 19:24:53 CEST
Restart Time: Wednesday, 29-Apr-2020 01:01:20 CEST
Parent Server Config. Generation: 1
Parent Server MPM Generation: 0
Server uptime: 18 hours 23 minutes 32 seconds
Server load: 0.04 0.26 0.18
1 requests currently being processed, 999 idle workers
Slot PID Stopping Connections Threads Async connections
total accepting busy idle writing keep-alive closing
0 10301 no 0 yes 0 200 0 0 0
1 10805 no 0 yes 0 200 0 0 0
2 25559 no 67 no 0 200 0 0 67
3 26063 no 1 yes 1 199 0 0 0
4 10806 no 0 yes 0 200 0 0 0
Sum 5 0 68 1 999 0 0 67
Some related config:
MaxKeepAliveRequests 1000
KeepAliveTimeout 5
ThreadLimit 200
ServerLimit 5
StartServers 1
MaxRequestWorkers 1000
MinSpareThreads 40
MaxSpareThreads 240
ThreadsPerChild 200
MaxConnectionsPerChild 0
AsyncRequestWorkerFactor 1
(I had to lower the AsyncRequestWorkerFactor from the default value (2)
because of issues with server closing some keep-alive connections
prematurely in some highly variable workload cases, causing issues with Java
clients using the Apache Http Client which doesn't seem to handle this
well.)
Best regards,
Petr