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From Chris Boyce <Chris.Bo...@cdw.com>
Subject Abandoned apache children with mod_jk
Date Fri, 21 Jun 2013 17:47:14 GMT
Hello,

I'm running apache 2.2.24 (worker MPM) with mod_jk 1.2.37 under Solaris 11, compiled as follows
(from config.log):

--with-included-apr --with-mpm=worker --enable-so --enable-rewrite --enable-headers --enable-proxy
--enable-proxy-http --enable-expires --enable-nonportable-atomics=yes --disable-include --disable-autoindex
--disable-imap --disable-userdir CC=/usr/sfw/bin/gcc

We are running Tomcat 7.0.32.

Since moving to Solaris 11 I'm noticing over time that apache children are getting left in
an idle state (and usually not showing up on the scoreboard at all) when doing graceful restarts. 
If I do a hard restart, the error_log notes that the process had to be forcibly killed:

[Wed May 15 11:41:24 2013] [warn] child process 10057 still did not exit, sending a SIGTERM
[Wed May 15 11:41:26 2013] [error] child process 10057 still did not exit, sending a SIGKILL

If I let apache go unchecked, it will eventually stop passing traffic completely and a hard
restart is required.  Example ps output looks like this:

nobody 24429 20925   0 11:43:59 ?           0:02 /usr/local/apache2/bin/httpd
-k start
nobody  9750 20925   0 23:59:02 ?           0:00 /usr/local/apache2/bin/httpd
-k start
nobody 20925  2440   0   May 15 ?           3:07 /usr/local/apache2/bin/httpd
-k start
nobody 24689 20925   0 11:47:52 ?           0:00 /usr/local/apache2/bin/httpd
-k start
nobody 24628 20925   0 11:46:18 ?           0:01 /usr/local/apache2/bin/httpd
-k start
nobody 24428 20925   0 11:43:39 ?           0:02 /usr/local/apache2/bin/httpd
-k start

Note PID 9750 is lingering, doing nothing according to pfiles and truss, and its timestamp
coincides with the last graceful restart (log rotation).  Two main differences between this
web server and ones that are working include:

a) This is Solaris 11 (vs. Solaris 10)
b) I have hardened apache by putting it in a Solaris 11 zone, and I'm starting apache as the
"nobody" user with the net_privaddr privilege so it can function as the parent process. 
It talks to Tomcat on another zone and everything works great (other than the problem described
here).

Apache has permission to write to /logs, and /log/apache2 is where I set these:

JkLogFile /logs/apache2/mod_jk.log
JkShmFile /logs/apache2/jk-runtime-status

And this.
PidFile /logs/apache2/run/httpd.pid


Can anyone think of a reason why children are not being recycled or getting stranded like
this over successive graceful restarts?  We do use multiple listeners, so I don't know if
I'm dealing with a locking/mutex/serialization type of issue.  I'm not a C programmer. 
There seems to be little info out there for Solaris platforms that's recent.  

I'd be happy to post more info if needed.  I appreciate your time.


Chris


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