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From Edward Quick <Edward.Qu...@iggroup.com>
Subject mod_jk question about lingering close_waits
Date Wed, 13 Jul 2011 15:10:11 GMT
Hi,

Apologies in advance if this is the wrong mailing list. I was unable to find one specific
to mod_jk and this looked the most relevant.

I have the following apache tomcat server configuration set up: Apache  2.2.3 , mod_jk 1.2.32
, and tomcat 6.0.32 running HelloWorld.war
If I send a request to http://remotehost/HelloWorld/index.jsp, I observe the following behaviour:


1 ) My tomcat AJP connector is listening on port 8010

TEST [root@remotehost]$ netstat -an | grep 8010
tcp        0      0 0.0.0.0:8010                0.0.0.0:*                   LISTEN


2) I make a request to http://remotehost/HelloWorld/index.jsp and see the apache establish
a connection to tomcat. The response comes back straightaway.

TEST [root@remotehost]$ netstat -an | grep 8010
tcp        0      0 0.0.0.0:8010                0.0.0.0:*                   LISTEN
tcp        0      0 10.34.2.140:8010            10.34.2.140:46792           ESTABLISHED
tcp        0      0 10.34.2.140:46792           10.34.2.140:8010            ESTABLISHED

3) After reaching KeepAliveTimeout on the Tomcat AJP connector, the connections change state:

TEST [root@ remotehost]$ netstat -an | grep 8010
tcp        0      0 0.0.0.0:8010                0.0.0.0:*                   LISTEN
tcp        0      0 10.34.2.140:8010            10.34.2.140:46792           FIN_WAIT2
tcp        1      0 10.34.2.140:46792           10.34.2.140:8010            CLOSE_WAIT

4) After about another minute, the FIN_WAIT2 is cleared, but the CLOSE_WAIT remains (on the
apache) until reaching net.ipv4.tcp_keepalive_time (which is set to 7200 seconds)

TEST [root@ remotehost]$ netstat -an | grep 8010
tcp        0      0 0.0.0.0:8010                0.0.0.0:*                   LISTEN
tcp        1      0 10.34.2.140:46792           10.34.2.140:8010            CLOSE_WAIT


Everything there looks fine except for the CLOSE_WAIT which lingers around for 2 hours until
it hits tcp_keepalive_time.
Adding JkOptions +DisableReuse will prevent the CLOSE_WAITs staying, but that is also said
to have a performance impact.

My question is if this is the expected tcpip state after the thread has finished, because
in JDBC I see the connections permanently ESTABLISHED or in TIME_WAIT.

Thanks for any help.

Ed.

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