On Thu, 30 Mar 2023 23:11:09 GMT, Patricio Chilano Mateo
<pchilanom...@openjdk.org> wrote:
>> Thank you for the concern.
>> The `startThread()` below which is called from `startThreads()` has the call
>> to `thread.ensureReady()` which waits until the target tested thread really
>> starts and sets the `threadReady` field. So, there is no race condition as
>> the `startThreads()` and `finishThreads()` are synchronized methods.
>>
>>
>> static private void startThread(int i) {
>> String name = "TestedThread" + i;
>> TestedThread thread = new TestedThread(name);
>> vts[i] = Thread.ofVirtual().name(name).start(thread);
>> thread.ensureReady();
>> threads[i] = thread;
>> log("# Java: started vthread: " + name);
>> }
>>
>> static synchronized private void startThreads() {
>> log("\n# Java: Starting vthreads");
>> for (int i = 0; i < VTHREADS_CNT; i++) {
>> sleep(1);
>> startThread(i);
>> }
>> }
>>
>> static private synchronized void finishThreads() {
>> try {
>> for (int i = 0; i < VTHREADS_CNT; i++) {
>> TestedThread thread = threads[i];
>> thread.letFinish();
>> vts[i].join();
>> }
>> } catch (InterruptedException e) {
>> throw new RuntimeException(e);
>> }
>> }
>>
>> Please, let me know if I'm missing anything.
>
> So the race I am talking about is between the main thread running
> finishThreads() and the launcher thread running startThreads(). The main
> thread could execute finishThreads() before the launcher executes
> startThreads(). If you comment out the two first sleeps in run_test_cycle()
> you can actually see the issue. Again, given that the sleeps are there it is
> an unlikely scheduling, but if we want to avoid depending on timing we can
> add that extra synchronization.
Sorry, I understood you incorrectly. You are right, there is this kind of race
here.
I've rearranges this area a little bit, and hope, it is cleaner now.
Now, both `startVirtualThreads()` and `finishVirtualThreads()` are invoked on
the main thread, so they do not need to be synchronized any more. Also, the
call to `ensureReady()` are moved to `finishVirtualThreads()` right before the
call to `letFinish()`.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/13133#discussion_r1154021018
