[15]RFR: 8238356: CodeHeap::blob_count() overestimates the number of blobs

[Tobias Hartmann]

Hi Rahul,

looks good to me. Please update the affected versions in the bug.

Thanks,
Tobias

On 17.02.20 09:12, Rahul Raghavan wrote:
> Hi,
> 
> Please review the following fix changeset.
> 
> <webrev> - http://cr.openjdk.java.net/~rraghavan/8238356/webrev.00/
> <JBS> -  https://bugs.openjdk.java.net/browse/JDK-8238356
> 
> Issue reported - CodeHeap::blob_count() can miscalculate the blob count.
> CodeHeap::_blob_count is only incremented, never decremented.
> 
> Webrev fix proposal, same as suggested by Aleksey Shipilev,
> is to decrement _blob_count on addition to the free list.
> 
> [src/hotspot/share/memory/heap.cpp]
>  void CodeHeap::add_to_freelist(HeapBlock* a) {
>    FreeBlock* b = (FreeBlock*)a;
>    size_t bseg = segment_for(b);
>    _freelist_length++;
> 
> + _blob_count--;
> + assert(_blob_count >= 0, "sanity");
> +
>    assert(b != _freelist, "cannot be removed twice");
> 
> Found no issues with precheckin, tier1 - tier5 testing.
> 
> 
> Thanks,
> Rahul