return from inside a @synchronized block in objective-c
@synchronized will automatically take down its exception-handling context when you return, and relinquish the lock. So the code you’ve written is fine.
synchronized
Synchronized method calls itself recursively. Is this broken?
In Java, synchronized locks are reentrant. Recall that a thread cannot acquire a lock owned by another thread. But a thread can acquire a lock that it already owns. Allowing a thread to acquire the same lock more than once enables reentrant synchronization. This describes a situation where synchronized code, directly or indirectly, invokes a … Read more
Is synchronized inherited in Java?
No, you will always have to write synchronized. If you call the synchronized method of the super class this will of course be a synchronized call. synchronized is not part of the method signature. See http://gee.cs.oswego.edu/dl/cpj/mechanics.html for detailed description from Doug Lea, Java threading boss (or so).
Do two synchronized methods execute simultaneously
If t1 access the m1 method (synchronized method), could t2 thread access m2 method (synchronized method) simultaneously? The synchronized keyword applies on object level, and only one thread can hold the lock of the object. So as long as you’re talking about the same object, then no, t2 will wait for t1 to release the … Read more
What is the synchronized method in Java [duplicate]
What is the synchronized method in Java [duplicate]
Should you synchronize the run method? Why or why not?
Synchronizing the run() method of a Runnable is completely pointless unless you want to share the Runnable among multiple threads and you want to sequentialize the execution of those threads. Which is basically a contradiction in terms. There is in theory another much more complicated scenario in which you might want to synchronize the run() … Read more
What is the difference between a synchronized method and synchronized block in Java? [duplicate]
A synchronized method uses the method receiver as a lock (i.e. this for non static methods, and the enclosing class for static methods). Synchronized blocks uses the expression as a lock. So the following two methods are equivalent from locking prospective: synchronized void mymethod() { … } void mymethod() { synchronized (this) { … } … Read more
Java synchronizing based on a parameter (named mutex/lock)
TL;DR: I use ConcurrentReferenceHashMap from the Spring Framework. Please check the code below. Although this thread is old, it is still interesting. Therefore, I would like to share my approach with Spring Framework. What we are trying to implement is called named mutex/lock. As suggested by Tudor’s answer, the idea is to have a Map … Read more
Why are synchronize expensive in Java?
Maybe it’s not as bad as you think It used to be terrible (which is possibly why you read that it was “very expensive”). These memes can take a long time to die out How expensive is synchronization? Because of the rules involving cache flushing and invalidation, a synchronized block in the Java language is … Read more