On Thu, 15 Aug 2024 04:11:47 GMT, David Holmes <dhol...@openjdk.org> wrote:
>> Greetings,
>>
>> Explicitly pin a virtual thread before acquiring the JFR string pool monitor
>> because migrating a carrier thread local event writer object onto another
>> carrier thread is impossible.
>>
>> During event commit, the thread is in a critical section because it has
>> loaded a carrier thread local event writer object. For virtual threads, a
>> contended monitor, such as a synchronized block, is a point where a thread
>> could become unmounted.
>>
>> A monitor guards the JFR string pool, but remounting a virtual thread onto
>> another carrier is impossible because of the event writer.
>>
>> Therefore, it's imperative to use explicit pin constructs to prevent
>> unmounting at this location.
>>
>> Testing: jdk_jfr
>>
>> Thanks
>> Markus
>
> src/jdk.jfr/share/classes/jdk/jfr/internal/StringPool.java line 93:
>
>> 91: private static long storeString(String s) {
>> 92: try {
>> 93: pinVirtualThread();
>
> The pin should be outside the try so that the finally can only happen if
> pinning was succesful.
Good point, thanks.
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PR Review Comment: https://git.openjdk.org/jdk/pull/20588#discussion_r1718199292
