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

Jon Masamitsu jon.masamitsu at oracle.com
Wed Mar 16 21:55:17 UTC 2016



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"?

Thanks for catching that.  Fixed.

> Line 1577:
>       log_trace(gc, metaspace)("    shrinking:  initSize: %.1fK 
> maximum_desired_capacity: %.1fK",
>                                MetaspaceSize / (double) K, 
> maximum_desired_capacity / (double) K);

And thanks for the review.

Jon

>
>  - 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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