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List:       openjdk-serviceability-dev
Subject:    Re: RFR: JDK-8074696: Remote debugging session hangs for several minutes when calling findBootType
From:       Jaroslav Bachorik <jaroslav.bachorik () oracle ! com>
Date:       2015-10-29 13:35:53
Message-ID: 563220B9.2030906 () oracle ! com
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On 28.10.2015 13:46, Andreas Eriksson wrote:
> Hi,
>
> Please review this change to JDI to address a performance bottleneck in
> findBootType for high delay networks.
>
> Bug:
> 8074696: Remote debugging session hangs for several minutes when calling
> findBootType
> https://bugs.openjdk.java.net/browse/JDK-8074696
>
> Webrev:
> http://cr.openjdk.java.net/~aeriksso/8074696/webrev.01/

Thumbs up! Just a small nit - before pushing, please, update the 
copyright year to 2015.

Cheers,

-JB-

>
> Description:
> VirtualMachineImpl.findBootType loops over all loaded classes and does a
> remote call to check if the signature matches.
> It will wait for the server response for each class before moving on to
> the next class, thus for many classes and high delay this will take a
> long time.
>
> Solution:
> Since we have a signature that should match, use
> retrieveClassesBySignature command that only returns matching classes.
> At worst we have to loop over the number of active classloader since we
> want the class loaded by the boot classloader (null class loader);
>
> Note:
> This bug was split in two, and this is only for the findBootType part.
> The more problematic visibleClasses change that was part of a previous
> review will be handled as a separate bug (JDK-8140515).
>
> Regards,
> Andreas

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