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1   /**
2    *
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *     http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing, software
14   * distributed under the License is distributed on an "AS IS" BASIS,
15   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16   * See the License for the specific language governing permissions and
17   * limitations under the License.
18   */
19  package org.apache.hadoop.hbase.util;
20  
21  import java.io.PrintWriter;
22  import java.lang.Thread.UncaughtExceptionHandler;
23  import java.util.concurrent.LinkedBlockingQueue;
24  import java.util.concurrent.ThreadFactory;
25  import java.util.concurrent.ThreadPoolExecutor;
26  import java.util.concurrent.TimeUnit;
27  import java.util.concurrent.atomic.AtomicInteger;
28  
29  import org.apache.commons.logging.Log;
30  import org.apache.commons.logging.LogFactory;
31  import org.apache.hadoop.classification.InterfaceAudience;
32  import org.apache.hadoop.util.ReflectionUtils;
33  
34  /**
35   * Thread Utility
36   */
37  @InterfaceAudience.Private
38  public class Threads {
39    protected static final Log LOG = LogFactory.getLog(Threads.class);
40    private static final AtomicInteger poolNumber = new AtomicInteger(1);
41    /**
42     * Utility method that sets name, daemon status and starts passed thread.
43     * @param t thread to run
44     * @return Returns the passed Thread <code>t</code>.
45     */
46    public static Thread setDaemonThreadRunning(final Thread t) {
47      return setDaemonThreadRunning(t, t.getName());
48    }
49  
50    /**
51     * Utility method that sets name, daemon status and starts passed thread.
52     * @param t thread to frob
53     * @param name new name
54     * @return Returns the passed Thread <code>t</code>.
55     */
56    public static Thread setDaemonThreadRunning(final Thread t,
57      final String name) {
58      return setDaemonThreadRunning(t, name, null);
59    }
60  
61    /**
62     * Utility method that sets name, daemon status and starts passed thread.
63     * @param t thread to frob
64     * @param name new name
65     * @param handler A handler to set on the thread.  Pass null if want to
66     * use default handler.
67     * @return Returns the passed Thread <code>t</code>.
68     */
69    public static Thread setDaemonThreadRunning(final Thread t,
70      final String name, final UncaughtExceptionHandler handler) {
71      t.setName(name);
72      if (handler != null) {
73        t.setUncaughtExceptionHandler(handler);
74      }
75      t.setDaemon(true);
76      t.start();
77      return t;
78    }
79  
80    /**
81     * Shutdown passed thread using isAlive and join.
82     * @param t Thread to shutdown
83     */
84    public static void shutdown(final Thread t) {
85      shutdown(t, 0);
86    }
87  
88    /**
89     * Shutdown passed thread using isAlive and join.
90     * @param joinwait Pass 0 if we're to wait forever.
91     * @param t Thread to shutdown
92     */
93    public static void shutdown(final Thread t, final long joinwait) {
94      if (t == null) return;
95      while (t.isAlive()) {
96        try {
97          t.join(joinwait);
98        } catch (InterruptedException e) {
99          LOG.warn(t.getName() + "; joinwait=" + joinwait, e);
100       }
101     }
102   }
103 
104 
105   /**
106    * @param t Waits on the passed thread to die dumping a threaddump every
107    * minute while its up.
108    * @throws InterruptedException
109    */
110   public static void threadDumpingIsAlive(final Thread t)
111   throws InterruptedException {
112     if (t == null) {
113       return;
114     }
115 
116     while (t.isAlive()) {
117       t.join(60 * 1000);
118       if (t.isAlive()) {
119         ReflectionUtils.printThreadInfo(new PrintWriter(System.out),
120             "Automatic Stack Trace every 60 seconds waiting on " +
121             t.getName());
122       }
123     }
124   }
125 
126   /**
127    * If interrupted, just prints out the interrupt on STDOUT, resets interrupt and returns
128    * @param millis How long to sleep for in milliseconds.
129    */
130   public static void sleep(long millis) {
131     try {
132       Thread.sleep(millis);
133     } catch (InterruptedException e) {
134       e.printStackTrace();
135       Thread.currentThread().interrupt();
136     }
137   }
138 
139   /**
140    * Sleeps for the given amount of time even if interrupted. Preserves
141    * the interrupt status.
142    * @param msToWait the amount of time to sleep in milliseconds
143    */
144   public static void sleepWithoutInterrupt(final long msToWait) {
145     long timeMillis = System.currentTimeMillis();
146     long endTime = timeMillis + msToWait;
147     boolean interrupted = false;
148     while (timeMillis < endTime) {
149       try {
150         Thread.sleep(endTime - timeMillis);
151       } catch (InterruptedException ex) {
152         interrupted = true;
153       }
154       timeMillis = System.currentTimeMillis();
155     }
156 
157     if (interrupted) {
158       Thread.currentThread().interrupt();
159     }
160   }
161 
162   /**
163    * Create a new CachedThreadPool with a bounded number as the maximum 
164    * thread size in the pool.
165    * 
166    * @param maxCachedThread the maximum thread could be created in the pool
167    * @param timeout the maximum time to wait
168    * @param unit the time unit of the timeout argument
169    * @param threadFactory the factory to use when creating new threads
170    * @return threadPoolExecutor the cachedThreadPool with a bounded number 
171    * as the maximum thread size in the pool. 
172    */
173   public static ThreadPoolExecutor getBoundedCachedThreadPool(
174       int maxCachedThread, long timeout, TimeUnit unit,
175       ThreadFactory threadFactory) {
176     ThreadPoolExecutor boundedCachedThreadPool =
177       new ThreadPoolExecutor(maxCachedThread, maxCachedThread, timeout,
178         unit, new LinkedBlockingQueue<Runnable>(), threadFactory);
179     // allow the core pool threads timeout and terminate
180     boundedCachedThreadPool.allowCoreThreadTimeOut(true);
181     return boundedCachedThreadPool;
182   }
183   
184   
185   /**
186    * Returns a {@link java.util.concurrent.ThreadFactory} that names each created thread uniquely,
187    * with a common prefix.
188    * @param prefix The prefix of every created Thread's name
189    * @return a {@link java.util.concurrent.ThreadFactory} that names threads
190    */
191   public static ThreadFactory getNamedThreadFactory(final String prefix) {
192     SecurityManager s = System.getSecurityManager();
193     final ThreadGroup threadGroup = (s != null) ? s.getThreadGroup() : Thread.currentThread()
194         .getThreadGroup();
195 
196     return new ThreadFactory() {
197       final AtomicInteger threadNumber = new AtomicInteger(1);
198       private final int poolNumber = Threads.poolNumber.getAndIncrement();
199       final ThreadGroup group = threadGroup;
200 
201       @Override
202       public Thread newThread(Runnable r) {
203         final String name = prefix + "-pool" + poolNumber + "-t" + threadNumber.getAndIncrement();
204         return new Thread(group, r, name);
205       }
206     };
207   }
208 
209   /**
210    * Same as {#newDaemonThreadFactory(String, UncaughtExceptionHandler)},
211    * without setting the exception handler.
212    */
213   public static ThreadFactory newDaemonThreadFactory(final String prefix) {
214     return newDaemonThreadFactory(prefix, null);
215   }
216 
217   /**
218    * Get a named {@link ThreadFactory} that just builds daemon threads.
219    * @param prefix name prefix for all threads created from the factory
220    * @param handler unhandles exception handler to set for all threads
221    * @return a thread factory that creates named, daemon threads with
222    *         the supplied exception handler and normal priority
223    */
224   public static ThreadFactory newDaemonThreadFactory(final String prefix,
225       final UncaughtExceptionHandler handler) {
226     final ThreadFactory namedFactory = getNamedThreadFactory(prefix);
227     return new ThreadFactory() {
228       @Override
229       public Thread newThread(Runnable r) {
230         Thread t = namedFactory.newThread(r);
231         if (handler != null) {
232           t.setUncaughtExceptionHandler(handler);
233         }
234         if (!t.isDaemon()) {
235           t.setDaemon(true);
236         }
237         if (t.getPriority() != Thread.NORM_PRIORITY) {
238           t.setPriority(Thread.NORM_PRIORITY);
239         }
240         return t;
241       }
242 
243     };
244   }
245 }