On 01.04.2009 09:46, Leon Brouwers wrote:
> Hello,
> 
> We have a large number of tomcats (5.5.26) on serveral servers. These
> tomcats communicate with a apache httpd on the same server using
> mod_jk (1.2.26). They all work fine until I restart apache httpd.
> Then randomly and certainly not all the time a tomcat stops working.
> Seeing the time the tomcat shuts down matches the time apache was
> restarted it seems to lead to the conclusion that the two events are
> related. For that reason I have patched my tomcats to be able so see
> with it's being stopped.
> 
> I have changed (source 1.2.26) 
> container/catalina/src/share/org/apache/catalina/core/StandardService.java
>
> 
On line 483 I have added a:
> Thread.dumpStack();
> 
> This gives me the following in the catalina.out during a httpd
> restart:
> 
> java.lang.Exception: Stack trace at
> java.lang.Thread.dumpStack(Thread.java:1158) at
> org.apache.catalina.core.StandardService.stop(StandardService.java:483)
>
> 
at org.apache.catalina.core.StandardServer.stop(StandardServer.java:734)
> at org.apache.catalina.startup.Catalina.stop(Catalina.java:602) at
> org.apache.catalina.startup.Catalina$CatalinaShutdownHook.run(Catalina.java:645)
>
> 
Apr 1, 2009 12:05:16 AM org.apache.catalina.core.StandardService stop
> INFO: Stopping service WebManager Apr 1, 2009 12:05:16 AM
> org.apache.catalina.core.StandardWrapper unload INFO: Waiting for 4
> instance(s) to be deallocated Apr 1, 2009 12:05:17 AM
> org.apache.catalina.core.StandardWrapper unload INFO: Waiting for 4
> instance(s) to be deallocated Apr 1, 2009 12:05:18 AM
> org.apache.catalina.core.StandardWrapper unload INFO: Waiting for 4
> instance(s) to be deallocated
> 
> What could be the reason the ShutdownHook is called? The apache
> restart happens thru a "kill -HUP" on the apache httpd main PID. So
> no signals should be sent to tomcat.

There is no technical reason for Tomcat to shut down, when you stop
Apache. I woiuld guess, the way you retrieve the PID for Apache gives
you multiple PIDs including the Tomcat PID. A normal kill on the Tomcat
java process will call the shutdown hook.

Make your script or whatever you use output the PIDs it kills and check,
to which processes they belong.

Regards,

Rainer


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