1 /* 2 * Copyright (c) 2023, 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 * @summary Stress test Thread.getStackTrace on virtual threads that are blocking or 27 * blocked on monitorenter 28 * @run main GetStackTraceALotWhenBlocked 500000 29 */ 30 31 /* 32 * @test 33 * @requires vm.debug == true & vm.continuations 34 * @run main/timeout=300 GetStackTraceALotWhenBlocked 50000 35 */ 36 37 import java.util.concurrent.ThreadLocalRandom; 38 import java.util.concurrent.atomic.AtomicBoolean; 39 40 public class GetStackTraceALotWhenBlocked { 41 42 public static void main(String[] args) throws Exception { 43 int iterations = args.length > 0 ? Integer.parseInt(args[0]) : 100_000; 44 45 var done = new AtomicBoolean(); 46 var lock = new Object(); 47 48 Runnable task = () -> { 49 long count = 0L; 50 while (!done.get()) { 51 synchronized (lock) { 52 pause(); 53 } 54 count++; 55 } 56 System.out.format("%s => %d%n", Thread.currentThread(), count); 57 }; 58 59 var thread1 = Thread.ofVirtual().start(task); 60 var thread2 = Thread.ofVirtual().start(task); 61 try { 62 for (int i = 0; i < iterations; i++) { 63 thread1.getStackTrace(); 64 pause(); 65 thread2.getStackTrace(); 66 pause(); 67 } 68 } finally { 69 done.set(true); 70 thread1.join(); 71 thread2.join(); 72 } 73 } 74 75 private static void pause() { 76 if (ThreadLocalRandom.current().nextBoolean()) { 77 Thread.onSpinWait(); 78 } else { 79 Thread.yield(); 80 } 81 } 82 }