On Wed, 5 Oct 2022 19:30:46 GMT, Alan Bateman <al...@openjdk.org> wrote:
>> test/jdk/java/lang/management/ThreadMXBean/VirtualThreadDeadlocks.java line
>> 30:
>>
>>> 28: * platform and virtual threads in deadlock
>>> 29: * @enablePreview
>>> 30: * @modules java.base/java.lang:+open java.management
>>
>> Can you explain the need for this change?
>
> That is jtreg foo to open java.lang, needed to access a private field.
ok
>> test/jdk/java/lang/management/ThreadMXBean/VirtualThreadDeadlocks.java line
>> 68:
>>
>>> 66: public static void main(String[] args) throws Exception {
>>> 67: // need at least two carrier threads due to pinning
>>> 68: VThreadRunner.ensureParallelism(2);
>>
>> In this test case why is there no need to maintain a reference to the
>> returned AutoCloseable? Isn't there a chance it can be collected and the old
>> parallelism value restored while the test is running.
>
> This test doesn't need to restore it so it doesn't keep a reference and not
> an issue if it is GC'ed.
It's not a matter of whether or not the test needs to restore it. It _will_
restore it if there is a GC, and if this happens before the test completes, it
could find itself without enough carrier threads.
>> test/lib/jdk/test/lib/thread/VThreadRunner.java line 176:
>>
>>> 174: if (!closed) {
>>> 175: closed = true;
>>> 176: pool.setParallelism(parallelism);
>>
>> What is the rationale for restoring the parallelism? It's just a test. Is
>> this really necessary? Are we reusing the JVM to run other tests, and even
>> if we are does it matter?
>
> Look at the ThreadAPI test as an example. It's a TestNG with dozens of test
> methods. All but one can run on single core systems.
Ok.
-------------
PR: https://git.openjdk.org/jdk/pull/10562
