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

[Coleen Phillimore]

On 9/30/16 3:46 PM, 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) {
> ...

     for (uint i = _small_block_min_size; i < _small_block_max_size; i++) {
       _small_lists[i - _small_block_min_size].set_size(i);
     }


In this loop I want 'i' to set the size.  The index of small_lists 
starts at 0 but the size is the size of the blocks.  This might make 
more sense like:

     for (uint i = _small_block_min_size; i < _small_block_max_size; i++) {
       int k = i - _small_block_min_size;  // zero based addressing
       _small_lists[k].set_size(i);
     }

Or something but the loops seem simple enough to me.

Coleen
>
> -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
>