CODEWITHSUNDEEP
javamultithreadingsynchronization
Ravi Parmar
Ravi Parmar

Reputation: 1452

About wait() and notify() methods of thread in java

I know the mechanism of wait() and notify() of thread, but I am unable to understand that why wait() and notify() methods should be in synchronized block? Is this mandatory?

Thanks in Advance!

Upvotes: 2

Views: 709

Answers (1)

Suraj Chandran
Suraj Chandran

Reputation: 24801

  1. Is synchronized mandatory while invoking wait/notify: Yes

  2. Why?: Consider that synchronizing was not required. That means that a thread A could call notify() exactly at the same time while the other thread B is calling wait()(on the same object). Suppose thread B has executed part of wait() method and is context-switched to serve thread A. So the internal data-structures of wait could be in corrupt state now. Now the notify() method essentially works on the same data-structures, which now is in invalid state. Hence the entire wait/notify could go for a toss. Synchronizing guarantees that no other method could call wait/notify if there is a call to one of them already on.

Upvotes: 4

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