quartz集群报错but has failed to stop it. This is very likely to create a memory leak.

在一台配置1核2G内存的阿里云服务器上运行quartz；执行定时任务报如下异常，而在本地开发环境中则正常运行。

10-Sep-2016 11:43:50.415 WARNING [localhost-startStop-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [faxian] appears to have started a thread named [logback-1] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:sun.misc.Unsafe.park(Native Method)java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1093)java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)java.lang.Thread.run(Thread.java:745)
10-Sep-2016 11:43:50.415 WARNING [localhost-startStop-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [faxian] appears to have started a thread named [Abandoned connection cleanup thread] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:java.lang.Object.wait(Native Method)java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)com.mysql.jdbc.AbandonedConnectionCleanupThread.run(AbandonedConnectionCleanupThread.java:43)
10-Sep-2016 11:43:50.416 WARNING [localhost-startStop-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [faxian] appears to have started a thread named [clusterQuartzScheduler_Worker-1] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:java.lang.Object.wait(Native Method)org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:568)
10-Sep-2016 11:43:50.417 WARNING [localhost-startStop-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [faxian] appears to have started a thread named [clusterQuartzScheduler_Worker-2] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:java.lang.Object.wait(Native Method)

根据异常，初步判断是内存溢出导致的问题。查看服务器内存使用情况

[root@test-server logs]#  free -htotal       used       free     shared    buffers     cachedMem:          1.8G       1.7G       84M       9.4M       154M       520M-/+ buffers/cache:       1.1G       759MSwap:           0B         0B         0B

于是查看quartz的配置

<task:executor id="quartzTaskExecutor" keep-alive="900" pool-size="10" queue-capacity="20" />

pool-size="10"，queue-capacity="20"。

然而根据实际情况并，连接池数量和容量并不需要这么大。改成pool-size="1"，queue-capacity="1"，再次启动不再报错。

查看服务器内存使用情况

[root@test-server logs]#  free -htotal       used       free     shared    buffers     cached
Mem:          1.8G       1.7G       141M       9.3M       154M       422M
-/+ buffers/cache:       1.1G       718M
Swap:           0B         0B         0B