RFR: 8334026: Provide a diagnostic PrintMemoryMapAtExit switch on Linux [v2]

[David Holmes]

On Tue, 18 Jun 2024 08:32:23 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> src/hotspot/share/nmt/memMapPrinter.cpp line 207:
>> 
>>> 205: static void print_thread_details_for_supposed_stack_address(const void* from, const void* to, outputStream* st) {
>>> 206: 
>>> 207:   ResourceMark rm;
>> 
>> Why was this needed to be added here? Shouldn't callers have any needed ResourceMarks?
>
> It is needed because in this function we call Thread::name() which for java threads returns an RA-allocated string. This issue popped up now because we are called without a ResourceMark at VM exit. I have not investigated closer since I think the Resourcemark makes sense here: The function does not export any RA-allocated memory but may be called in a loop many times.

Okay. I was trying to find where the existing callers have their RM and it is not obvious.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19660#discussion_r1644137807