When should I use SynchronousQueue

java concurrency blockingqueue
Anton picture Anton · Dec 21, 2011 · Viewed 31.7k times · Source 
new SynchronousQueue()
new LinkedBlockingQueue(1)

What is the difference? When I should use SynchronousQueue against LinkedBlockingQueue with capacity 1?

Answer

jtahlborn picture jtahlborn · Dec 21, 2011

the SynchronousQueue is more of a handoff, whereas the LinkedBlockingQueue just allows a single element. The difference being that the put() call to a SynchronousQueue will not return until there is a corresponding take() call, but with a LinkedBlockingQueue of size 1, the put() call (to an empty queue) will return immediately.

I can't say that i have ever used the SynchronousQueue directly myself, but it is the default BlockingQueue used for the Executors.newCachedThreadPool() methods. It's essentially the BlockingQueue implementation for when you don't really want a queue (you don't want to maintain any pending data).

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