Removing intrinsic of Thread.isInterrupted() (original) (raw)

Yumin Qi yumin.qi at oracle.com
Mon Feb 24 17:46:37 PST 2014

Hi, Compiler team

I worked on this bug: 6498581:ThreadInterruptTest3 produces wrong output on Windows. This is a problem thread sleep wakes up spuriously due to a race condition between os::interrupt and os::is_interruped. Detail please see bug comments.

https://bugs.openjdk.java.net/browse/JDK-6498581

The fix is (without removing intrinsic, but intend to remove it) : http://cr.openjdk.java.net/~minqi/6498581/webrev00/

One problem is that Thread.isInterrupted() is intrinsic and there is chance that code like

boolean a = Thread.currentThread().isInterrupted(); boolean b = Thread.interrupted();

Will get different value. (fast/slow path) I tried to remove the intrinsic code and done a test using following code. The result showed there is no difference by removing the intrinsic of Thread.isInterrupted().

// test performance of removing Thread.isInterrupted() inlining public class TestThreadInterrupted { public static void main(String... args) { Thread t = new Thread () { public void run() { boolean isInt = false; while (!isInt) { try { Thread.sleep(30); } catch (InterruptedException ie) { isInt = true; } } } };

     t.start();
     // run
     long start, finish, isum = 0L, osum = 0L;
     int  NUM = 20000;
     for (int j = 0; j < 100; j++) {
     isum = 0L;
     for (int i = 0; i < NUM; i++) {
         start = System.currentTimeMillis();
         t.isInterrupted();
         finish = System.currentTimeMillis();
         isum += (finish - start);
     }

     System.out.println("Total cost of " + NUM + " calls is " + isum

And found there is no difference on Solaris-x64/sparcv9, Windows(32/64), linux(32/64) before and after the removing of intrinsic Thread.isInterrupted().

Should I remove the intrinsic?

Data (no major difference for both with/without intrinsic):

1)windows : .... Total cost of 20000 calls is 2 ms Total cost of 20000 calls is 1 ms Total cost of 20000 calls is 1 ms Total cost of 20000 calls is 1 ms Total cost of 20000 calls is 2 ms Total cost of 20000 calls is 1 ms Total cost of 20000 calls is 2 ms Total cost of 20000 calls is 2 ms Total cost of 20000 calls is 2 ms Total cost of 20000 calls is 0 ms Total cost of 20000 calls is 2 ms Total cost of 20000 calls is 2 ms Average 1 ms

  1. Solaris-x64 .... Total cost of 20000 calls is 3 ms Total cost of 20000 calls is 1 ms Total cost of 20000 calls is 4 ms Total cost of 20000 calls is 6 ms Total cost of 20000 calls is 6 ms Total cost of 20000 calls is 5 ms Total cost of 20000 calls is 7 ms Total cost of 20000 calls is 5 ms Total cost of 20000 calls is 5 ms Total cost of 20000 calls is 1 ms Total cost of 20000 calls is 3 ms Total cost of 20000 calls is 2 ms Total cost of 20000 calls is 3 ms Total cost of 20000 calls is 3 ms Total cost of 20000 calls is 5 ms Total cost of 20000 calls is 4 ms Total cost of 20000 calls is 4 ms Total cost of 20000 calls is 7 ms Average 4 ms

  2. Linux:

.... Total cost of 20000 calls is 30 ms Total cost of 20000 calls is 29 ms Total cost of 20000 calls is 26 ms Total cost of 20000 calls is 26 ms Total cost of 20000 calls is 26 ms Total cost of 20000 calls is 24 ms Total cost of 20000 calls is 29 ms Total cost of 20000 calls is 25 ms Total cost of 20000 calls is 20 ms Average 24 ms

Thanks Yumin

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