RFR (M) 8164921: Memory leaked when instrumentation.retransformClasses() is called repeatedly

Dmitry Samersoff dmitry.samersoff at oracle.com
Fri Sep 30 20:18:54 UTC 2016


Coleen,

1.

Never mind, should read bug report more carefully. Sorry!

-Dmitry

On 2016-09-30 22:46, Dmitry Samersoff wrote:
> Coleen,
> 
> My $.02
> 
> 1.
> metaspace.cpp:279 we have assert(word_size >= _small_block_min_size,
> ...)  so at 868 and 895
> if (word_size < SmallBlocks::small_block_min_size()) {
> probably should be asserts as well
> 
> 
> 2.
> It might be better to rewrite loops at metaspace.cpp 261,268
>   for (uint i = _small_block_min_size; i < _small_block_max_size; i++) {
> as
>   for (uint i = 0;
>         i < (_small_block_max_size - _small_block_min_size);  ++i) {
> ...
> 
> -Dmitry
> 
> On 2016-09-30 22:02, Coleen Phillimore wrote:
>> Summary: Return Metablocks smaller than dictionary's dark matter.
>>
>> This change contributed by Jon Masamitsu and myself.  To reclaim "dark
>> matter" this change adds an array of small blocks by size, created
>> lazily, to return Metablocks smaller than the BinaryTreeDictionary
>> entry's minimum size.   This change also fixed a bug in small object
>> double free and adds debugging code to check for this case.
>>
>> With this change, the submitted test case runs indefinitely.   Also
>> passed rbt tier 1-5 testing.
>>
>> open webrev at http://cr.openjdk.java.net/~coleenp/8164921.01/webrev
>> bug link https://bugs.openjdk.java.net/browse/JDK-8164921
>>
>> Thanks,
>> Coleen and Jon
> 
> 


-- 
Dmitry Samersoff
Oracle Java development team, Saint Petersburg, Russia
* I would love to change the world, but they won't give me the sources.


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