症状

When running JIRA on Tomcat 6.0.24, there are periodic deadlocks. Thread dumps taken when JIRA is unresponsive show deadlocks like:

Found one Java-level deadlock:
=============================
"http-8080-6":
  waiting to lock monitor 0x039664f4 (object 0x12aa4008, a org.apache.catalina.loader.WebappClassLoader),
  which is held by "http-8080-5"
"http-8080-5":
  waiting to lock monitor 0x0396655c (object 0x2a2005a8, a java.lang.String),
  which is held by "http-8080-6"

原因

There is a known bug in version 6.0.24 of tomcat that causes deadlocks in applications that use their own classloaders (such as JIRA). See Apache's bug tracker for more information.

ソリューション

Upgrade to version 6.0.26 or higher of Tomcat and reinstall the JIRA ear-war, or install JIRA's latest stand-alone distribution.