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From Henri Gomez <>
Subject JK add-ons to fix problems with HUNG tomcats...
Date Wed, 24 Sep 2003 07:48:04 GMT
Hi to all,

After the yesterday post of David Rees (mod_jk does not detect a hung 
Tomcat), I take a look at ajp/jk and make some works to fix the problem.

In fact the problem is in jk since the begining as jk use sockets in 
blocking mode.

The works I conducted :

- Modify ajp protocol on java side to accept a PING message (0x08).
   This message will be answered by low level ajp layer by a ..

- On the jk (not jk2 for now) I added 3 optional timeouts :

   a connect_timeout, which when set will send a PING request
   after connection and wait for PONG reply up to connect_timeout ms.

   a prepost_timeout, which when set will send a PING request before
   trying to send the real request to tomcat.

   in fine I added the long awaited reply_timeout, which will make
   jk wait up to reply_timeout ms before failing in error.

With such 3 timeouts (optional in, we should be
able to detect any problem with remote tomcats and as such make a
better use of tomcat clusters via Load-Balancing.

If nobody object, I'll commit it this afternoon CET for review and

Note, that by default jk works as before....

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