Hi Kim,
On 05/09/2024 06:10, 김민주 wrote:
If I use an external lock, T1 will block in the |await()| state, but T2,
T3, and T4 will be waiting for the external lock rather than entering
the |await()| state in |put()|. This would prevent me from simulating
the specific behavior I’m trying to test.
I understand. But my point is that waking up callers in exactly the
same order they have have arrived may not be of much interest since you
would need first to ensure that they arrive in exactly that
proper order.
I’d appreciate your thoughts on whether this behavior (where a newly
arriving thread can overtake a waiting thread) is expected or if it’s
worth further investigation. As this is my first attempt to contribute
to OpenJDK, I’m eager to learn from the process and would love to help
resolve the issue if necessary.
I am not sure how strong the "fairness" constraint is.
Typically for monitors, when a thread is signaled after the monitor
is released "it competes in the usual manner with other threads for the
right to synchronize on the object"
https://docs.oracle.com/en/java/javase/22/docs/api/java.base/java/lang/Object.html#wait(long,int)
That said, we're speakings of locks here - and the only thing I
could find (in ReentrantLock) is that if fairness is set, then
"under contention, locks favor granting access to the
longest-waiting thread", but note that "fairness of locks does
not guarantee fairness of thread scheduling. Thus, one of many
threads using a fair lock may obtain it multiple times in
succession while other active threads are not progressing and
not currently holding the lock."
https://docs.oracle.com/en/java/javase/22/docs/api/java.base/java/util/concurrent/locks/ReentrantLock.html
I am not an expert of the java.util.concurrent package, and
hopefully others in this list will be able to provide more
insights.
Also, since English is not my first language, I hope my previous emails
didn’t come across as rude or unclear. If they did, I sincerely
apologize, as it was never my intention to be disrespectful. I’m still
learning how to communicate effectively in this space, and I appreciate
your understanding and patience.
Hey - you're welcome - and I found your emails quite clear.
But English is not my first language either ;-)
best regards,
-- daniel
Thank you for your time and guidance.
Best regards,
