We are still investigating what specific classloader reads that would trigger
the repeated reload of the web-inf/lib/*.jars.
One example we found is the use of
javax.xml.transform.TransformerFactory.newInstance(). One of its features is to
determine the implementation by searching for the configuration specified by
META-INF/services/javax.xml.transform.TransformerFactory in jars available to
the runtime.
It seems users of Tomcat 9 would need to understand the management of the jar
resource handles when using the TransformerFactory class - assuming it is
triggering the reload of all the related application jars - which if happening
enough can cause the high cpu/disk usage as we observed in our performance
tests.
Thanks
-----Original Message-----
From: Mark Thomas <ma...@apache.org>
Sent: Thursday, October 10, 2019 3:54 AM
To: users@tomcat.apache.org
Subject: Re: Performance test with Tomcat 9 shows increased cpu/disk usage
because of repeated opening/closing of jars in WEB-INF/lib
On 09/10/2019 22:58, Rhuberg,Anthony wrote:
> StandardRoot.gc() unconditionally closes the web application jars in Tomcat
> 9... every 10s by default or configurable by changing
> backgroundProcessorDelay.
>
> So then the problem is.... Our web application is calling
> class.getResourceAsStream() to read some static files... and this is causing
> the jars to be read again?
It sounds like it.
> This was not a problem with Tomcat 7 because the jars were not closed if they
> were read within the jarOpenInterval setting?
Or that the frequency that the JARs were closed was low enough that the
performance impact was not noticed.
Mark
>
> Thanks,
> Tony
>
> -----Original Message-----
> From: Mark Thomas <ma...@apache.org>
> Sent: Wednesday, October 09, 2019 5:32 PM
> To: users@tomcat.apache.org
> Subject: Re: Performance test with Tomcat 9 shows increased cpu/disk
> usage because of repeated opening/closing of jars in WEB-INF/lib
>
> On 09/10/2019 21:03, Rhuberg,Anthony wrote:
>> This seems to alleviate the issue... in context.xml (sc-test#sc.xml)
>> <Context docBase="${STP_HOME}/app/webapps/Clinicals"
>> swallowOutput="true" backgroundProcessorDelay="90">
>>
>> Not sure if this is the context reload trigger... i.e. the
>> webappLoader.backgroundProcess method is triggered every 90 seconds...
>
> It isn't. It is StandardRoot.gc() that is unloading the cached JAR entries.
>
> Mark
>
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