1 /*
   2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  */
  22 
  23 /*
  24  * This file is available under and governed by the GNU General Public
  25  * License version 2 only, as published by the Free Software Foundation.
  26  * However, the following notice accompanied the original version of this
  27  * file:
  28  *
  29  * Written by Martin Buchholz and Jason Mehrens with assistance from
  30  * members of JCP JSR-166 Expert Group and released to the public
  31  * domain, as explained at
  32  * http://creativecommons.org/publicdomain/zero/1.0/
  33  */
  34 
  35 /*
  36  * @test
  37  * @summary Only one thread should be created when a thread needs to
  38  * be kept alive to service a delayed task waiting in the queue.
  39  * @library /test/lib
  40  */
  41 
  42 import static java.util.concurrent.TimeUnit.MILLISECONDS;
  43 
  44 import java.util.concurrent.ScheduledThreadPoolExecutor;
  45 import java.util.concurrent.ThreadFactory;
  46 import java.util.concurrent.atomic.AtomicLong;
  47 import jdk.test.lib.Utils;
  48 
  49 public class ThreadRestarts {
  50     static final long LONG_DELAY_MS = Utils.adjustTimeout(10_000);
  51     static final long FAR_FUTURE_MS = 10 * LONG_DELAY_MS;
  52 
  53     public static void main(String[] args) throws Exception {
  54         test(false);
  55         test(true);
  56     }
  57 
  58     private static void test(boolean allowTimeout) throws Exception {
  59         CountingThreadFactory ctf = new CountingThreadFactory();
  60         ScheduledThreadPoolExecutor stpe
  61             = new ScheduledThreadPoolExecutor(10, ctf);
  62         try {
  63             // schedule a dummy task in the "far future"
  64             Runnable nop = new Runnable() { public void run() {}};
  65             stpe.schedule(nop, FAR_FUTURE_MS, MILLISECONDS);
  66             stpe.setKeepAliveTime(1L, MILLISECONDS);
  67             stpe.allowCoreThreadTimeOut(allowTimeout);
  68             MILLISECONDS.sleep(12L);
  69         } finally {
  70             stpe.shutdownNow();
  71             if (!stpe.awaitTermination(LONG_DELAY_MS, MILLISECONDS))
  72                 throw new AssertionError("timed out");
  73         }
  74         if (ctf.count.get() > 1)
  75             throw new AssertionError(
  76                 String.format("%d threads created, 1 expected",
  77                               ctf.count.get()));
  78     }
  79 
  80     static class CountingThreadFactory implements ThreadFactory {
  81         final AtomicLong count = new AtomicLong(0L);
  82 
  83         public Thread newThread(Runnable r) {
  84             count.getAndIncrement();
  85             Thread t = new Thread(r);
  86             t.setDaemon(true);
  87             return t;
  88         }
  89     }
  90 }