Mantis - Resin
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2368 crash always 01-25-08 04:44 06-11-08 18:53
closed 3.0.24  
none 3.2.0  
0002368: Whenever heapdump is taken, resin cluster breaks down
Whenever we take a heapdump with command
jdk1.5.0_14/bin/jmap -heap:format=b PID

whole resin cluster (2-6 instances) becomes unresponsive and is unusable.
Quite often all resins in cluster needs to be restarted to make the site to serve again.

If Apaches with mod_caucho are restarted, the site works for some minutes, but breaks again.

Also amount of active threads increases hugely in each resin instance while taking the heapdump.

03-27-08 10:17   
This is a difficult issue.

A heap dump freezes the JVM for the time that it takes to take the heap dump. If the heap is large, this can be a significant period of time.

For the cluster issue, we may need to change the messaging/threading behavior for writing backup copies. Currently, Resin uses the request thread to write the session backups, which can cause problem when a backup server goes down. Any updates to that backup model will need to wait for the 3.2.x branch (after 3.1.6)
06-11-08 18:53   
In 3.2, the sessions are now stored back using a separate thread, so even if a backend server is unresponsive, the primary servers will not need to wait.