Request for Review (xs) - 8151845: Comment in globals.hpp for MetaspaceSize is incorrect.

Jon Masamitsu jon.masamitsu at oracle.com
Wed Mar 16 22:12:12 UTC 2016


I updated the webrev to include Derek's suggestion and seem to have
clobbered the first version of the webrev in the process. Fortunately,
the changes is so small (hint, hint to potential reviewers) that it matters
very little.

http://cr.openjdk.java.net/~jmasa/8151845/webrev.01/

Jon

On 03/16/2016 12:16 PM, Derek White wrote:
> Hi Jon,
>
> That looks good.
>
> There's a log message that might need updating also? "initSize" => 
> "initThreshold"?
> Line 1577:
>       log_trace(gc, metaspace)("    shrinking:  initSize: %.1fK 
> maximum_desired_capacity: %.1fK",
>                                MetaspaceSize / (double) K, 
> maximum_desired_capacity / (double) K);
>
>  - Derek
>
> On 3/15/16 12:56 PM, Jon Masamitsu wrote:
>> https://bugs.openjdk.java.net/browse/JDK-8151845
>>
>> Change the description for MetaspaceSize in globals.hpp thus
>>
>> -          "Initial size of Metaspaces (in 
>> bytes)")                          \
>> +          "Initial threshold (in bytes) at which a garbage 
>> collection "     \
>> +          "is done to reduce Metaspace 
>> usage")                              \
>>
>> Garbage collections will be done specifically to recover metadata
>> (the GC finds dead classloaders and identifies metadata associated
>> with the classloaders that is no longer used).  Triggering a GC for
>> metadata recovery is done if the amount of metadata in use exceeds
>> a threshold that is dynamically adjusted (threshold is raised or lowered
>> depending on the amount of Metaspace made available for new metadata
>> allocations).  MetaspaceSize is the initial threshold.
>>
>> http://cr.openjdk.java.net/~jmasa/8141845/webrev.00/
>>
>> I am very open to suggestions for a better description.
>>
>> My apologies to Yasumasa Suenaga for not settling this issue
>> when he raised it almost 2 years ago.
>>
>> http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2014-April/009916.html 
>>
>>
>> Jon
>>
>>
>

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