关于ScheduledExecutorService执行一段时间之后就不执行的问

最近写了个程序，程序中使用到了ScheduledExecutorService的scheduleAtFixedRate方法，用于定时执行任务，但是发现程序运行一段时间之后定时任务不执行了，查看日志和perfcounter都没有看到任何异常，比较郁闷。最后看了一下JDK的源码，在源码的Java doc中的发现了如下一句话：

If any execution of the task encounters an exception, subsequent executions are suppressed.Otherwise, the task will only terminate via cancellation or termination of the executor.
简单总结就是：如果定时任务执行过程中遇到发生异常，则后面的任务将不再执行。
我们可以做个实验验证一下：
先看下面一段代码：

<p style="margin-top: 0px; margin-bottom: 10px; padding-top: 0px; padding-bottom: 0px;"><span class="com" style="color: rgb(136, 0, 0);">/**</span>

<span class="com" style="color: rgb(136, 0, 0);"> *  [Copyright]</span>
<span class="com" style="color: rgb(136, 0, 0);"> *  @author  QiFuguang </span>
<span class="com" style="color: rgb(136, 0, 0);"> *  Aug 25, 2014 9:48:41 PM	</span>
<span class="com" style="color: rgb(136, 0, 0);"> */</span>

<span class="kwd" style="color: rgb(0, 0, 136);">package</span><span class="pln" style="color: rgb(0, 0, 0);"> com</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">winwill</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">xx</span><span class="pun" style="color: rgb(102, 102, 0);">;</span>

<span class="kwd" style="color: rgb(0, 0, 136);">import</span><span class="pln" style="color: rgb(0, 0, 0);"> <a target=_blank href="http://lib.csdn.net/base/17" class="replace_word" title="Java EE知识库" target="_blank" style="color: rgb(223, 52, 52); text-decoration: none; font-weight: bold;">Java</a></span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">util</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">concurrent</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="typ" style="color: rgb(102, 0, 102);">Executors</span><span class="pun" style="color: rgb(102, 102, 0);">;</span>
<span class="kwd" style="color: rgb(0, 0, 136);">import</span><span class="pln" style="color: rgb(0, 0, 0);"> java</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">util</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">concurrent</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="typ" style="color: rgb(102, 0, 102);">ScheduledExecutorService</span><span class="pun" style="color: rgb(102, 102, 0);">;</span>
<span class="kwd" style="color: rgb(0, 0, 136);">import</span><span class="pln" style="color: rgb(0, 0, 0);"> java</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">util</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">concurrent</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="typ" style="color: rgb(102, 0, 102);">TimeUnit</span><span class="pun" style="color: rgb(102, 102, 0);">;</span>

<span class="kwd" style="color: rgb(0, 0, 136);">public</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">class</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">Test</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span>
<span class="pln" style="color: rgb(0, 0, 0);">    </span><span class="kwd" style="color: rgb(0, 0, 136);">private</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">final</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">static</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">ScheduledExecutorService</span><span class="pln" style="color: rgb(0, 0, 0);"> scheduler </span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">Executors</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">newSingleThreadScheduledExecutor</span><span class="pun" style="color: rgb(102, 102, 0);">();</span>

<span class="pln" style="color: rgb(0, 0, 0);">    </span><span class="kwd" style="color: rgb(0, 0, 136);">public</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">static</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">void</span><span class="pln" style="color: rgb(0, 0, 0);"> main</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="typ" style="color: rgb(102, 0, 102);">String</span><span class="pun" style="color: rgb(102, 102, 0);">[]</span><span class="pln" style="color: rgb(0, 0, 0);"> args</span><span class="pun" style="color: rgb(102, 102, 0);">)</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span>
<span class="pln" style="color: rgb(0, 0, 0);">        scheduler</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">scheduleAtFixedRate</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="kwd" style="color: rgb(0, 0, 136);">new</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">Runnable</span><span class="pun" style="color: rgb(102, 102, 0);">()</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span>
<span class="pln" style="color: rgb(0, 0, 0);">            </span><span class="lit" style="color: rgb(0, 102, 102);">@Override</span>
<span class="pln" style="color: rgb(0, 0, 0);">            </span><span class="kwd" style="color: rgb(0, 0, 136);">public</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">void</span><span class="pln" style="color: rgb(0, 0, 0);"> run</span><span class="pun" style="color: rgb(102, 102, 0);">()</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span>
<span class="pln" style="color: rgb(0, 0, 0);">                </span><span class="kwd" style="color: rgb(0, 0, 136);">int</span><span class="pun" style="color: rgb(102, 102, 0);">[]</span><span class="pln" style="color: rgb(0, 0, 0);"> s </span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">new</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">int</span><span class="pun" style="color: rgb(102, 102, 0);">[</span><span class="lit" style="color: rgb(0, 102, 102);">1</span><span class="pun" style="color: rgb(102, 102, 0);">];</span>
<span class="pln" style="color: rgb(0, 0, 0);">                </span><span class="typ" style="color: rgb(102, 0, 102);">System</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="kwd" style="color: rgb(0, 0, 136);">out</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">println</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="str" style="color: rgb(0, 136, 0);">"OK"</span><span class="pun" style="color: rgb(102, 102, 0);">);</span>
<span class="pln" style="color: rgb(0, 0, 0);">                </span><span class="typ" style="color: rgb(102, 0, 102);">System</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="kwd" style="color: rgb(0, 0, 136);">out</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">println</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="pln" style="color: rgb(0, 0, 0);">s</span><span class="pun" style="color: rgb(102, 102, 0);">[</span><span class="lit" style="color: rgb(0, 102, 102);">1</span><span class="pun" style="color: rgb(102, 102, 0);">]);</span><span class="pln" style="color: rgb(0, 0, 0);">  </span><span class="com" style="color: rgb(136, 0, 0);">// 数组越界</span>
<span class="pln" style="color: rgb(0, 0, 0);">            </span><span class="pun" style="color: rgb(102, 102, 0);">}</span>
<span class="pln" style="color: rgb(0, 0, 0);">        </span><span class="pun" style="color: rgb(102, 102, 0);">},</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="lit" style="color: rgb(0, 102, 102);">0</span><span class="pun" style="color: rgb(102, 102, 0);">,</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="lit" style="color: rgb(0, 102, 102);">2</span><span class="pun" style="color: rgb(102, 102, 0);">,</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">TimeUnit</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">SECONDS</span><span class="pun" style="color: rgb(102, 102, 0);">);</span>
<span class="pln" style="color: rgb(0, 0, 0);">    </span><span class="pun" style="color: rgb(102, 102, 0);">}</span>
<span class="pun" style="color: rgb(102, 102, 0);">}</span>

</p>

这段代码的执行效果如下:

关于ScheduledExecutorService执行一段时间之后不在执行的问题 - 黯然神伤 - WinWill2014

可以看到定时任务只执行了一次，因为第一次执行就遇到了数组越界异常，后面的任务被取消了。

再看如下代码：

<p style="margin-top: 0px; margin-bottom: 10px; padding-top: 0px; padding-bottom: 0px;"><span class="com" style="color: rgb(136, 0, 0);">/**</span>

<span class="com" style="color: rgb(136, 0, 0);"> *  [Copyright]</span>
<span class="com" style="color: rgb(136, 0, 0);"> *  @author  QiFuguang </span>
<span class="com" style="color: rgb(136, 0, 0);"> *  Aug 25, 2014 9:48:41 PM	</span>
<span class="com" style="color: rgb(136, 0, 0);"> */</span>

<span class="kwd" style="color: rgb(0, 0, 136);">package</span><span class="pln" style="color: rgb(0, 0, 0);"> com</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">winwill</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">xx</span><span class="pun" style="color: rgb(102, 102, 0);">;</span>

<span class="kwd" style="color: rgb(0, 0, 136);">import</span><span class="pln" style="color: rgb(0, 0, 0);"> java</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">util</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">concurrent</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="typ" style="color: rgb(102, 0, 102);">Executors</span><span class="pun" style="color: rgb(102, 102, 0);">;</span>
<span class="kwd" style="color: rgb(0, 0, 136);">import</span><span class="pln" style="color: rgb(0, 0, 0);"> java</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">util</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">concurrent</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="typ" style="color: rgb(102, 0, 102);">ScheduledExecutorService</span><span class="pun" style="color: rgb(102, 102, 0);">;</span>
<span class="kwd" style="color: rgb(0, 0, 136);">import</span><span class="pln" style="color: rgb(0, 0, 0);"> java</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">util</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">concurrent</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="typ" style="color: rgb(102, 0, 102);">TimeUnit</span><span class="pun" style="color: rgb(102, 102, 0);">;</span>

<span class="kwd" style="color: rgb(0, 0, 136);">public</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">class</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">Test</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span>
<span class="pln" style="color: rgb(0, 0, 0);">    </span><span class="kwd" style="color: rgb(0, 0, 136);">private</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">final</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">static</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">ScheduledExecutorService</span><span class="pln" style="color: rgb(0, 0, 0);"> scheduler </span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">Executors</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">newSingleThreadScheduledExecutor</span><span class="pun" style="color: rgb(102, 102, 0);">();</span>

<span class="pln" style="color: rgb(0, 0, 0);">    </span><span class="kwd" style="color: rgb(0, 0, 136);">public</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">static</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">void</span><span class="pln" style="color: rgb(0, 0, 0);"> main</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="typ" style="color: rgb(102, 0, 102);">String</span><span class="pun" style="color: rgb(102, 102, 0);">[]</span><span class="pln" style="color: rgb(0, 0, 0);"> args</span><span class="pun" style="color: rgb(102, 102, 0);">)</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span>
<span class="pln" style="color: rgb(0, 0, 0);">        scheduler</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">scheduleAtFixedRate</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="kwd" style="color: rgb(0, 0, 136);">new</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">Runnable</span><span class="pun" style="color: rgb(102, 102, 0);">()</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span>
<span class="pln" style="color: rgb(0, 0, 0);">            </span><span class="lit" style="color: rgb(0, 102, 102);">@Override</span>
<span class="pln" style="color: rgb(0, 0, 0);">            </span><span class="kwd" style="color: rgb(0, 0, 136);">public</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">void</span><span class="pln" style="color: rgb(0, 0, 0);"> run</span><span class="pun" style="color: rgb(102, 102, 0);">()</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span>
<span class="pln" style="color: rgb(0, 0, 0);">                </span><span class="kwd" style="color: rgb(0, 0, 136);">try</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span>
<span class="pln" style="color: rgb(0, 0, 0);">                    </span><span class="kwd" style="color: rgb(0, 0, 136);">int</span><span class="pun" style="color: rgb(102, 102, 0);">[]</span><span class="pln" style="color: rgb(0, 0, 0);"> s </span><span class="pun" style="color: rgb(102, 102, 0);">=</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">new</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">int</span><span class="pun" style="color: rgb(102, 102, 0);">[</span><span class="lit" style="color: rgb(0, 102, 102);">1</span><span class="pun" style="color: rgb(102, 102, 0);">];</span>
<span class="pln" style="color: rgb(0, 0, 0);">                    </span><span class="typ" style="color: rgb(102, 0, 102);">System</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="kwd" style="color: rgb(0, 0, 136);">out</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">println</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="str" style="color: rgb(0, 136, 0);">"OK"</span><span class="pun" style="color: rgb(102, 102, 0);">);</span>
<span class="pln" style="color: rgb(0, 0, 0);">                    </span><span class="typ" style="color: rgb(102, 0, 102);">System</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="kwd" style="color: rgb(0, 0, 136);">out</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">println</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="pln" style="color: rgb(0, 0, 0);">s</span><span class="pun" style="color: rgb(102, 102, 0);">[</span><span class="lit" style="color: rgb(0, 102, 102);">1</span><span class="pun" style="color: rgb(102, 102, 0);">]);</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">// 数组越界</span>
<span class="pln" style="color: rgb(0, 0, 0);">                </span><span class="pun" style="color: rgb(102, 102, 0);">}</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="kwd" style="color: rgb(0, 0, 136);">catch</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="typ" style="color: rgb(102, 0, 102);">Throwable</span><span class="pln" style="color: rgb(0, 0, 0);"> t</span><span class="pun" style="color: rgb(102, 102, 0);">)</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="pun" style="color: rgb(102, 102, 0);">{</span>
<span class="pln" style="color: rgb(0, 0, 0);">                    </span><span class="typ" style="color: rgb(102, 0, 102);">System</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="kwd" style="color: rgb(0, 0, 136);">out</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">println</span><span class="pun" style="color: rgb(102, 102, 0);">(</span><span class="str" style="color: rgb(0, 136, 0);">"Error"</span><span class="pun" style="color: rgb(102, 102, 0);">);</span>
<span class="pln" style="color: rgb(0, 0, 0);">                </span><span class="pun" style="color: rgb(102, 102, 0);">}</span>

<span class="pln" style="color: rgb(0, 0, 0);">            </span><span class="pun" style="color: rgb(102, 102, 0);">}</span>
<span class="pln" style="color: rgb(0, 0, 0);">        </span><span class="pun" style="color: rgb(102, 102, 0);">},</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="lit" style="color: rgb(0, 102, 102);">0</span><span class="pun" style="color: rgb(102, 102, 0);">,</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="lit" style="color: rgb(0, 102, 102);">2</span><span class="pun" style="color: rgb(102, 102, 0);">,</span><span class="pln" style="color: rgb(0, 0, 0);"> </span><span class="typ" style="color: rgb(102, 0, 102);">TimeUnit</span><span class="pun" style="color: rgb(102, 102, 0);">.</span><span class="pln" style="color: rgb(0, 0, 0);">SECONDS</span><span class="pun" style="color: rgb(102, 102, 0);">);</span>
<span class="pln" style="color: rgb(0, 0, 0);">    </span><span class="pun" style="color: rgb(102, 102, 0);">}</span>
<span class="pun" style="color: rgb(102, 102, 0);">}</span>

</p>

运行效果如下：

加了try/catch之后可以看到定时任务没有被取消。

关于ScheduledExecutorService执行一段时间之后就不执行的问

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