FAQ

Mark Thomas wrote:
Roy McMorran wrote:
Hello all,

I'm seeing frequent cases where requests sent via mod_jk to Tomcat will
hang indefinitely. The request will never return to Apache and the
client will eventually time out. There are no error messages.

In my test case I run wget against various URLs until the hang occurs
(usually within 2-3 minutes). Here are the last few entries from my
mod_jk.log file (JkLogLevel = trace):

[Thu Dec 04 13:28:08.509 2008] [27224:1] [debug]
ajp_connection_tcp_send_message::jk_ajp_common.c (911): 00c0 FF 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 - ................
[Thu Dec 04 13:28:08.510 2008] [27224:1] [trace]
ajp_connection_tcp_send_message::jk_ajp_common.c (928): exit
[Thu Dec 04 13:28:08.510 2008] [27224:1] [debug]
ajp_send_request::jk_ajp_common.c (1325): (ajp13) request body to send 0
- request body to resend 0
[Thu Dec 04 13:28:08.511 2008] [27224:1] [trace]
ajp_send_request::jk_ajp_common.c (1422): exit
[Thu Dec 04 13:28:08.511 2008] [27224:1] [trace]
ajp_get_reply::jk_ajp_common.c (1613): enter
[Thu Dec 04 13:28:08.511 2008] [27224:1] [trace]
ajp_connection_tcp_get_message::jk_ajp_common.c (953): enter

Beyond this point there is no activity. There are never any error
messages generated, not in mod_jk.log, catalina.out, nor in the Apache
logs.

There is a thread dump of Tomcat (after the hang begins) at:
http://www.mdibl.org/~mcmorran/tomcat_thread_dump.txt

This is a pretty simple setup, both Apache & Tomcat are running on the
same host, so there is no firewall issue. No load balancing, just one
worker defined.

workers.properties file:
worker.list=ajp13
worker.ajp13.type=ajp13
worker.ajp13.host=localhost
worker.ajp13.port=8009
worker.ajp13.socket_timeout=120

(have tried with and without the socket_timeout parameter - makes no
difference)

My server.xml file is at:
http://www.mdibl.org/~mcmorran/server.xml.txt

(I've tried various settings (or none) for connectionTimeout inside the
AJP connector - makes no difference)

mod_jk related parts of my httpd.conf file are at:
http://www.mdibl.org/~mcmorran/httpd.conf.txt

Version info:
Server: Solaris 10
Apache: 2.2.6
mod_jk: 1.2.25
Tomcat: 6.0.14
libtcnative: 1.10
Java: 1.5.0_14

I'm running Tomcat under jsvc. The JVM gets 2G of memory (there are 8G
total on the system) - I don't think there's any memory issue. I'm in
test mode so I'm the only user; there's virtually no CPU load on the box.

I've reached a dead end here -I'm hoping someone on the list may have
some ideas. Thanks for any help you may be able to provide.
Have you tried:
JkOptions +DisableReuse
?

Mark
Hi Mark, thanks for the reply.

I hadn't tried DisableReuse - the documentation at
http://tomcat.apache.org/connectors-doc/reference/apache.html led me to
believe that 1) it would likely be very detrimental to performance and
2) it probably doesn't apply my situation (no firewall, no network
involved at all).

Nevertheless, I gave it a go just now. Unfortunately it made no difference.

Thanks,
-r

--

Roy McMorran
Systems Administrator
MDI Biological Laboratory
mcmorran@mdibl.org


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