1 /* 2 * Copyright (c) 2023, 2024, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24 /* 25 * @test 26 * @bug 8322818 27 * @summary Stress test Thread.getStackTrace on a virtual thread that is pinned 28 * @requires vm.debug != true 29 * @modules java.base/java.lang:+open 30 * @library /test/lib 31 * @run main/othervm GetStackTraceALotWhenPinned 500000 32 */ 33 34 /* 35 * @test 36 * @requires vm.debug == true 37 * @modules java.base/java.lang:+open 38 * @library /test/lib 39 * @run main/othervm/timeout=300 GetStackTraceALotWhenPinned 200000 40 */ 41 42 import java.time.Instant; 43 import java.util.concurrent.atomic.AtomicInteger; 44 import java.util.concurrent.locks.LockSupport; 45 import jdk.test.lib.thread.VThreadRunner; 46 import jdk.test.lib.thread.VThreadPinner; 47 48 public class GetStackTraceALotWhenPinned { 49 50 public static void main(String[] args) throws Exception { 51 // need at least two carrier threads when main thread is a virtual thread 52 if (Thread.currentThread().isVirtual()) { 53 VThreadRunner.ensureParallelism(2); 54 } 55 56 int iterations = Integer.parseInt(args[0]); 57 var barrier = new Barrier(2); 58 59 // Start a virtual thread that loops doing Thread.yield and parking while pinned. 60 // This loop creates the conditions for the main thread to sample the stack trace 61 // as it transitions from being unmounted to parking while pinned. 62 var thread = Thread.startVirtualThread(() -> { 63 boolean timed = false; 64 for (int i = 0; i < iterations; i++) { 65 // wait for main thread to arrive 66 barrier.await(); 67 68 Thread.yield(); 69 boolean b = timed; 70 VThreadPinner.runPinned(() -> { 71 if (b) { 72 LockSupport.parkNanos(Long.MAX_VALUE); 73 } else { 74 LockSupport.park(); 75 } 76 }); 77 timed = !timed; 78 } 79 }); 80 81 long lastTimestamp = System.currentTimeMillis(); 82 for (int i = 0; i < iterations; i++) { 83 // wait for virtual thread to arrive 84 barrier.await(); 85 86 thread.getStackTrace(); 87 LockSupport.unpark(thread); 88 89 long currentTime = System.currentTimeMillis(); 90 if ((currentTime - lastTimestamp) > 500) { 91 System.out.format("%s %d remaining ...%n", Instant.now(), (iterations - i)); 92 lastTimestamp = currentTime; 93 } 94 } 95 } 96 97 /** 98 * Alow threads wait for each other to reach a common barrier point. This class does 99 * not park threads that are waiting for the barrier to trip, instead it spins. This 100 * makes it suitable for tests that use LockSupport.park or Thread.yield. 101 */ 102 private static class Barrier { 103 private final int parties; 104 private final AtomicInteger count; 105 private volatile int generation; 106 107 Barrier(int parties) { 108 this.parties = parties; 109 this.count = new AtomicInteger(parties); 110 } 111 112 void await() { 113 int g = generation; 114 if (count.decrementAndGet() == 0) { 115 count.set(parties); 116 generation = g + 1; 117 } else { 118 while (generation == g) { 119 Thread.onSpinWait(); 120 } 121 } 122 } 123 124 } 125 }