流程大致如下：
（0）环境要求，JDK1.6及以上
（1）先找到进程的PID，Windows下，打开进程管理器，按照名字排序，可以找到叫做javaw.exe的进程（java虚拟机进程一律叫做javaw.exe），要找出哪个是你的进程，记住当前进程列表，然后重启你的进程，PID刷新过的那个即是你的进程。
（2）在CMD下运行：jstack pid，jstack会在console上打出一系列信息
（3）分析上述信息
"startQuertz_Worker-2" prio=6 tid=0x000000006201f000 nid=0x14b0 runnable [0x0000000068b9e000] java.lang.Thread.State: RUNNABLE at java.net.SocketInputStream.socketRead0(Native Method) at java.net.SocketInputStream.read(SocketInputStream.java:129) at com.sun.mail.util.TraceInputStream.read(TraceInputStream.java:97) at java.io.BufferedInputStream.fill(BufferedInputStream.java:218) at java.io.BufferedInputStream.read(BufferedInputStream.java:237) - locked <0x0000005896b7a708> (a java.io.BufferedInputStream) at com.sun.mail.iap.ResponseInputStream.read0(ResponseInputStream.java:81) at com.sun.mail.iap.ResponseInputStream.readResponse(ResponseInputStream.java:67) at com.sun.mail.iap.Response.<init>(Response.java:83) at com.sun.mail.imap.protocol.IMAPResponse.<init>(IMAPResponse.java:48) at com.sun.mail.imap.protocol.IMAPResponse.readResponse(IMAPResponse.java:122) at com.sun.mail.imap.protocol.IMAPProtocol.readResponse(IMAPProtocol.java:230) at com.sun.mail.iap.Protocol.command(Protocol.java:263) - locked <0x0000005896b74cb8> (a com.sun.mail.imap.protocol.IMAPProtocol) at com.sun.mail.imap.protocol.IMAPProtocol.fetch(IMAPProtocol.java:1234) at com.sun.mail.imap.protocol.IMAPProtocol.fetch(IMAPProtocol.java:1226) at com.sun.mail.imap.protocol.IMAPProtocol.fetchBody(IMAPProtocol.java:1028) at com.sun.mail.imap.protocol.IMAPProtocol.fetchBody(IMAPProtocol.java:1023) at com.sun.mail.imap.IMAPInputStream.fill(IMAPInputStream.java:101) - locked <0x0000005896bb77d0> (a java.lang.Object) at com.sun.mail.imap.IMAPInputStream.read(IMAPInputStream.java:158) - locked <0x0000005897da6540> (a com.sun.mail.imap.IMAPInputStream) at com.sun.mail.imap.IMAPInputStream.read(IMAPInputStream.java:184) at com.sun.mail.util.BASE64DecoderStream.getByte(BASE64DecoderStream.java:337) at com.sun.mail.util.BASE64DecoderStream.decode(BASE64DecoderStream.java:230) at com.sun.mail.util.BASE64DecoderStream.read(BASE64DecoderStream.java:135) at java.io.FilterInputStream.read(FilterInputStream.java:90) at javax.mail.internet.MimeBodyPart.saveFile(MimeBodyPart.java:805) at com.detao.dtma.email.EmailReciver.processAttachment(EmailReciver.java:244) at com.detao.dtma.email.EmailReciver.processMsg(EmailReciver.java:140) at com.detao.dtma.email.EmailReciver.processMsg(EmailReciver.java:93) at com.detao.dtma.email.EmailReciver.processMessages(EmailReciver.java:69) at com.detao.dtma.email.EmailReciver.processMessages(EmailReciver.java:50) at com.detao.dtma.email.EmailReciverMgr.run(EmailReciverMgr.java:31) at sun.reflect.GeneratedMethodAccessor2511.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.util.MethodInvoker.invoke(MethodInvoker.java:273) at org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean$MethodInvokingJob.executeInternal(MethodInvokingJobDetailFactoryBean.java:264) at org.springframework.scheduling.quartz.QuartzJobBean.execute(QuartzJobBean.java:86) at org.quartz.core.JobRunShell.run(JobRunShell.java:203) at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:520) "startQuertz_Worker-1" prio=6 tid=0x0000000064022800 nid=0x3a4 waiting for monitor entry [0x0000000068a9f000] java.lang.Thread.State: BLOCKED (on object monitor) at java.lang.Object.wait(Native Method) - waiting on <0x0000005872f40648> (a java.lang.Object) at org.quartz.simpl.SimpleThreadPool.getNextRunnable(SimpleThreadPool.java:428) - locked <0x0000005872f40648> (a java.lang.Object) at org.quartz.simpl.SimpleThreadPool.access$000(SimpleThreadPool.java:47) at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:518) "startQuertz_Worker-0" prio=6 tid=0x0000000060f15000 nid=0x13e8 waiting for monitor entry [0x000000006899f000] java.lang.Thread.State: BLOCKED (on object monitor) at java.lang.Object.wait(Native Method) - waiting on <0x0000005872f40648> (a java.lang.Object) at org.quartz.simpl.SimpleThreadPool.getNextRunnable(SimpleThreadPool.java:428) - locked <0x0000005872f40648> (a java.lang.Object) at org.quartz.simpl.SimpleThreadPool.access$000(SimpleThreadPool.java:47) at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:518) "Store userCache Spool Thread" daemon prio=6 tid=0x000000006194f000 nid=0x1354 waiting on condition [0x000000006889f000] java.lang.Thread.State: TIMED_WAITING (sleeping) at java.lang.Thread.sleep(Native Method) at net.sf.ehcache.store.DiskStore.spoolAndExpiryThreadMain(DiskStore.java:634) at net.sf.ehcache.store.DiskStore.access$900(DiskStore.java:68) at net.sf.ehcache.store.DiskStore$SpoolAndExpiryThread.run(DiskStore.java:1110)
最后定位到错误行
at com.detao.dtma.email.EmailReciverMgr.run(EmailReciverMgr.java:31)
找到相应代码
public class EmailReciverMgr extends TimerTask {
/* 邮件接收器 一个邮件接收器对应一个邮箱 */
private java.util.List<EmailReciver> recivers;
/* 程序是否正在进行 */
private boolean running = false;
public void setRecivers(java.util.List<EmailReciver> recivers) {
this.recivers = recivers;
}
@Override
public void run() {
// 如果正在运行就返回，否则运行
if (running) {
return;
}
try {
running = true;
// 循环邮件接收器
for (EmailReciver reciver : recivers) {
// 处理邮件
reciver.processMessages();
}
} catch (Exception e) {
e.printStackTrace();
} finally {
// 运行完毕设置为false，以便进行下一次运行
running = false;
}
}
}
程序本身没有问题，问题出现在了调用上，两个定时器都有自己的定时策略，分别调用了两次，造成相互等待，形成死锁。
此问题的难点在于问题的定位，问题的发生具有不确定性，有时候半月不发生，有时候一天发生多次，定位不到问题，后台没有任何报错，最后jstack，终于定位到了问题，找到问题之后，解决就好办了。