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javamultithreadingconcurrencybusy-loop

Why blocking instead of looping?

What are some reasons why writing the following piece of code is considered bad practice?

  while (someList.isEmpty()) {
    try {
      Thread.currentThread().sleep(100);
    }
    catch (Exception e) {}
  }
  // Do something to the list as soon as some thread adds an element to it.

To me, picking an arbitrary value to sleep is not good practice, and I would use a BlockingQueue in this situation, but I'd like to know if there is more than one reason why one shouldn't write such code.

Solution

  • It imposes an average delay of 50 milliseconds before the event is acted on, and it wakes up 10 times a second when there's no event to handle. If neither of those things particularly matter, then it's just inelegant.