multithreading - How to Count the number of threads completed in java without polling for the threads status -

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in java program, have start n number of threads, , each thread performs operation . these threads continue operating in parallel. have monitor, number of threads have completed operation , mark progress of operation in percentage.

the method, think of poll through entire thread array , keep checking status, unless nodes have completed execution. however, wastage of cpu, other possible way achieve this?

easy. have each thread (or each thread's runnable) increment shared atomicinteger instance when completes.

other alternatives include:

  • using semaphore or countdownlatch
  • using callback; e.g. using events , event listener
  • using wait() , notify().

but careful. if using counter determine if threads have finished need deal case thread dies due uncaught exception. can using uncaught exception handler.


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