Re: JDBC HIGH CPU and Restart Issue

[Pete Hall <pete@xxxxxxxxxxxxxx>]

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pholm@xxxxxxxxxxxxxxxxx wrote:
>    All,
>    I've found some related info on google but nothing definitive.
>    Environment:  V5R4 iSeries acting as database with Tomcat and
>    JDBC/connection pools hosted on a Windows server.
>    Problem:  Occasionally the QZDASOINT job servicing the JDBC will consume
>    most CPU.  I've lowered the QZDASOINIT priority to 30 to lessen the impact
>    to interactive users.  However the problem and high cpu persist
>    occasionally.  If we do a ENDJOB on these jobs they are restarted
>    automatically and resume using too much CPU.  If we end Tomcat the jobs go
>    away.  Restarting Tomcat restarts the QZDASOINIT jobs.  We have connection
>    pool code but we do not have any logic to reissue JDBC queries to the
>    system.  I suspect it to be an i5 issue.  Has anyone experienced the issue
>    or have insight?
>    Thanks, Paul Holm

If you download tomcat, bin/catalina.sh contains code that sets the
server job priority to 6. That's one issue. It should never be that low.

A second problem might be heap size and garbage collection cycles
processing during startup. The heap should (I am advised) be large
enough to handle application startup without garbage collection.

A third issue might be paging, if the storage pool isn't large enough,
but be aware that java does a lot more paging than a (for instance) rpg
program. Look at this after the first two are handled.

- --
Pete Hall
pete@xxxxxxxxxxxxxx
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