问题
In order to synchronize/queue access to a shared resource, I am about to use a Semaphore, aided by a wait loop.
In order not to run into CPU pegging, I would like to sleep() a little bit inside that while loop.
I searched the http://developer.android.com reference and found two such sleep() functions and I am confused as to which one fits which scenario:
- Thread.sleep()
- SystemClock.sleep()
Which one better suits the case I described and why?
回答1:
First of all, do you really need a wait loop? You can typically solve your problems using proper notifications, i.e. having an Object, calling wait() and notify() on it or other means (like a blocking queue, or Semaphore.acquire() in your case).
That said, if you really want a polling loop (which you really shouldn't do unless you have to), I'd stick with Thread.sleep(). There's not much of a difference, as the documentation says, except that you have the option to interrupt a Thread.sleep(). Don't rid yourself the option to do so.
Note that in case of Thread.sleep(), you're going to have to catch that exception - if you're extremely lazy, you'll probably stick with SystemClock.sleep().
回答2:
The truth is:
Thread.sleep(n) could be interrupted within a call like AsyncTask by using asyncTask.cancel(true)
SystemClock.sleep(n) seems to ignore any interrupted command, thus it could be a risk of memory leak when you use it similar like here: https://github.com/square/leakcanary/blob/master/leakcanary-sample/src/main/java/com/example/leakcanary/MainActivity.java
来源：https://stackoverflow.com/questions/5837910/systemclock-sleep-vs-thread-sleep-while-waiting-for-a-semaphore-loop