On Thu, 15 Jan 2026 17:42:33 GMT, Patricio Chilano Mateo <[email protected]> wrote:
> Please review the following patch. This fixes a bug in how we handle state > changes for the timed `Object.wait` case in `afterYield`, which can leave a > virtual thread stuck in the `BLOCKED` state. It can be triggered by two > consecutive calls to timed `Object.wait`, if the first call receives a > notification and the second call relies on the timeout task to wake up the > thread. I added the full sequence of events that leads to the vthread getting > stuck in JBS. > > The fix is to check for `notified` and attempt to change the state to > `BLOCKED` inside the synchronized block. This guarantees that we don't change > the state of an already new timed `Object.wait` call. > > The PR includes a new test which reproduces the issue when run several times > in mach5. It's a hybrid of my original repro test and another one created by > @AlanBateman. > > Thanks, > Patricio @pchilano I took a look at this out of interest but there is nothing Hotspot related to review. The state machine for VTs is too complex for me to comment on the actual fix - though I understand how the timedWaitLock forces the calls to be serialized. It did make we wonder why the timed-park doesn't need any locking. Can't it have a similar problem if the virtual thread is unparked before the carrier can set the state to TIMED_PARK? ------------- PR Comment: https://git.openjdk.org/jdk/pull/29255#issuecomment-3757721807
