mod_cluster in JBCS httpd 2.4 experiences issues with low smax setting

Solution Verified - Updated -


  • We are moving from httpd 2.2 to JBCS httpd 2.4. smax is set low in our modcluster configuration. And now with light load we see connections immediately fail:
[Tue Apr 21 10:20:41.123443 2020] [:debug] [pid 27147:tid 139853093992192] mod_proxy_cluster.c(2479): proxy: byrequests balancer DONE (http:///
[Tue Apr 21 10:20:41.123456 2020] [proxy:debug] [pid 27147:tid 139853093992192] proxy_util.c(1919): AH00924: worker http:/// shared already initialized
[Tue Apr 21 10:20:41.123460 2020] [proxy:debug] [pid 27147:tid 139853093992192] proxy_util.c(1976): AH00926: worker http:/// local already initialized
[Tue Apr 21 10:20:41.123464 2020] [proxy:debug] [pid 27147:tid 139853093992192] mod_proxy.c(1254): [client] AH01143: Running scheme balancer handler (attempt 0)
[Tue Apr 21 10:20:41.125726 2020] [proxy:error] [pid 27147:tid 139853093992192] (70007)The timeout specified has expired: AH00941: HTTP: failed to acquire connection for ()


  • JBoss Enterprise Application Platform (EAP)
  • JBCS httpd 2.4.x
  • mod_cluster

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