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Posted to notifications@ignite.apache.org by GitBox <gi...@apache.org> on 2022/11/30 09:01:27 UTC
[GitHub] [ignite] aarmam opened a new issue, #10409: Ignite semaphore release vs. close
aarmam opened a new issue, #10409:
URL: https://github.com/apache/ignite/issues/10409
Hi,
I have a question about race condition on closing semaphores. As I understand semaphores are not removed automatically and must therfore be closed manually. Lets say two threads want to change some object and try to aquire semaphore for it:
```java
IgniteSemaphore semaphore = ignite.semaphore(objectId, 1, true, true);
if (semaphore.tryAcquire(5, TimeUnit.SECONDS)) {
try {
changeObject(objectId);
} finally {
semaphore.release(); // First thread releases semaphore
// Second thread aquires semaphore
semaphore.close(); // First thread closes semaphore
}
}
```
1) What happens if first thread tries to close semaphore while second thread has aquired it?
2) But my main quiestion is - can I close the semaphote without calling release before it? So second thread cannot aquire it.
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[GitHub] [ignite] aarmam commented on issue #10409: Ignite semaphore release vs. close
Posted by GitBox <gi...@apache.org>.
aarmam commented on issue #10409:
URL: https://github.com/apache/ignite/issues/10409#issuecomment-1331871201
> In most cases you don't want to close a semaphore. You create it once and reuse.
Yes but in our case the changed object is relatively short lived and therefore aquired semaphore is always with unique id.
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[GitHub] [ignite] ptupitsyn commented on issue #10409: Ignite semaphore release vs. close
Posted by GitBox <gi...@apache.org>.
ptupitsyn commented on issue #10409:
URL: https://github.com/apache/ignite/issues/10409#issuecomment-1331861534
1. It will be closed and removed from the cluster, even if acquired by other threads.
2. Yes, you can close without releasing.
In most cases you don't want to close a semaphore. You create it once and reuse.
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[GitHub] [ignite] aarmam closed issue #10409: Ignite semaphore release vs. close
Posted by GitBox <gi...@apache.org>.
aarmam closed issue #10409: Ignite semaphore release vs. close
URL: https://github.com/apache/ignite/issues/10409
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