On Fri, 16 Feb 2024 06:09:40 GMT, David Holmes <dhol...@openjdk.org> wrote:
>> Serguei Spitsyn has updated the pull request incrementally with one
>> additional commit since the last revision:
>>
>> review: JDWP monitor_info spec clarification; removed debugging code from
>> objmonusage001
>
> src/hotspot/share/prims/jvmtiEnvBase.cpp line 1500:
>
>> 1498: for (int i = 0; i < nWait; i++) {
>> 1499: if (waiter == nullptr || (i != 0 && waiter ==
>> mon->first_waiter())) {
>> 1500: // robustness: the waiting list has gotten smaller
>
> We are at a safepoint so I don't see how the wait list can shrink. I
> initially thought perhaps a waiter could timeout, but the code that does the
> timed park is wrapped in ` ThreadBlockInVMPreprocess` which will block at a
> safepoint if one is active.
Thank you for the question.
The `nWait` count we got from the `mon->waiters()` can include the threads that
are re-entering the monitor after being notified. Here we are correcting the
actual number of the waiting threads by excluding those re-entering the
monitor. The comment need an update to explain it.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/17680#discussion_r1494556207
