i was experiencing strange behaviour using tomcat 6.0.13 + mod-cluster 1.1.3 + apache 2.2.21.
I have 1 apache and 3 tomcat instances.
Using this configuration tomcat side:
I saw that stopping one on the tomcat instances, httpd starts asap to have a very high CPU usage. Also restarting tomcat the CPU usage stays high.
Strange thing...i found that setting "stickySessionForce" to true, this behaviour doesn't happen.
I continued my investigation and I fixed the issue compiling mod_manager and mod_proxy_cluster on the host with httpd (not sure if the issue was in the mod_manager or in mod_proxy_cluster but if needed i can try).
So now i'm pretty confused :-) since using .so modules from this package http://downloads.jboss.org/mod_cluster//1.1.3.Final/mod_cluster-1.1.3.Final-linux2-x64-so.tar.gz i have the issue aforementioned, but compiling mod-cluster source i don't have it.
[root]# httpd -V
Server version: Apache/2.2.21 (Unix)
Server built: Jan 12 2012 15:28:45
Server's Module Magic Number: 20051115:30
Server loaded: APR 1.2.7, APR-Util 1.2.7
Compiled using: APR 1.2.7, APR-Util 1.2.7
Server MPM: Worker
threaded: yes (fixed thread count)
forked: yes (variable process count)
Server compiled with....
-D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)
To note that from mod_cluster i'm using just these .so:
About mod_proxy, mod_proxy_ajp, mod_proxy_http i use tha ones coming from httpd
since otherwise i have issues (stickysession doesn't work).
At this point i don't know if i'm installing mod-cluster in the right way or if i'm missing something.
Could you help me in understanding what is happening and where i'm doing wrong ?