RFR: 8368124: Show useful thread names in ASAN reports [v6]

[David Holmes]

On Wed, 24 Sep 2025 16:09:24 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> On Linux, ASAN only shows some internal thread designation on reports, e.g. `T49`, which is useless.
>> 
>> This patch adds the ability to see the real internal JVM thread names or user-supplied Java thread names in ASAN. This makes it possible to correlate ASAN reports with hs-err file reports (if ASAN is run with `halt_on_error=0` to give us a chance to get an hs-err file) or with a thread dump done beforehand.
>> 
>> Note that it can only show up to 15 characters, though. Therefore, the patch tries to be smart about names that end in digits: such numbers are preserved such that the truncation happens in the middle of the name, e.g.:
>> 
>> `"MyAllocationWorkerThread#4411"` -> `"MyAllocat..4411"`
>> 
>> This latter improvement now also applies to thread names in gdb, since they are subject to the same limitation.
>> 
>> For a detailed analysis of why the old version, using libpthread's `pthread_setname_np`, is not sufficient for thread names in ASAN, please see the issue description.
>> 
>> -----
>> 
>> Some examples from ASAN report: 
>> 
>> Before:
>> 
>> WRITE of size 8 at 0x7b749d2d9190 thread T49
>> 
>> 
>> Now:
>> 
>> WRITE of size 8 at 0x7bfc2f0d8380 thread T49 (MyThread#0)
>> 
>> 
>> 
>> ==593899==ERROR: AddressSanitizer: attempting free .. in thread T76 (MyAllocati..29)
>
> Thomas Stuefe has updated the pull request incrementally with one additional commit since the last revision:
> 
>   some more tests

Simplified spot-fix looks good - thanks.

You missed my follow up re the redundancy of `Linux::_pthread_setname_np`.

test/hotspot/gtest/runtime/test_os_linux.cpp line 38:

> 36: 
> 37: #include <sys/prctl.h>
> 38: #include <sys/mman.h>

Nit: alphabetic order please

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PR Review: https://git.openjdk.org/jdk/pull/27395#pullrequestreview-3265344997
PR Review Comment: https://git.openjdk.org/jdk/pull/27395#discussion_r2377518644