On Tue, 1 Sep 2026 03:46:31 GMT, Shiv Shah <[email protected]> wrote:
>> The SA sizes a stack chunk like any fixed size instance, the layout helper
>> only covers the header part, so the region walk steps into the copied stack
>> data, fails to parse it as an object and gives up on the rest of the region.
>> whatever lives after the chunk never makes it into the dump, that is what
>> the hprof verification failures were. the fix reads the chunk’s own size
>> field and computes the footprint the same way the vm does, header plus stack
>> plus the gc bitmap words. the heap dump test comes off the virtual problem
>> list since it passes now.
>>
>>
>> ---------
>> - [x] I confirm that I make this contribution in accordance with the
>> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai).
>
> Shiv Shah has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Mirror the hotspot size helpers
src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/InstanceStackChunkKlass.java
line 55:
> 53: }
> 54:
> 55: public long getObjectSize(Oop object) {
Suggestion:
@Override
public long getObjectSize(Oop object) {
src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/InstanceStackChunkKlass.java
line 74:
> 72: long bits = bitmapSizeInBits(stackSizeInWords);
> 73: return ((bits + bitsPerWord - 1) & ~(bitsPerWord - 1)) / bitsPerWord;
> 74: }
According to HotSpot, should this method return `bitmapSizeInBits() /
bitsPerWord` (not aligned)?
inline size_t InstanceStackChunkKlass::bitmap_size(size_t stack_size_in_words) {
return bitmap_size_in_bits(stack_size_in_words) >> LogBitsPerWord;
}
src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/InstanceStackChunkKlass.java
line 79:
> 77: VM vm = VM.getVM();
> 78: return stackSizeInWords * (vm.getBytesPerWord() /
> vm.getHeapOopSize());
> 79: }
According to HotSpot, the result of this method should be aligned.
inline size_t InstanceStackChunkKlass::bitmap_size_in_bits(size_t
stack_size_in_words) {
// Need one bit per potential narrowOop* or oop* address.
size_t size_in_bits = stack_size_in_words << (LogBitsPerWord -
LogBitsPerHeapOop);
return align_up(size_in_bits, BitsPerWord);
}
You can use `VM.alignUp()` to align.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/32525#discussion_r3900953416
PR Review Comment: https://git.openjdk.org/jdk/pull/32525#discussion_r3901049029
PR Review Comment: https://git.openjdk.org/jdk/pull/32525#discussion_r3901066241
