死锁

　　项目遇到的死锁问题

项目假死

问题描述：
　　在linux服务器中，springboot项目运行一段时间后，ps -ef|grep java发现项目进程在，但是打开日志，请求项目接口，发现服务器没有反应，好像死了一样。什么原因呢？
解决：
　　问题出现后，通过 jstack 进程id 发现，出现了死锁问题。

JNI global references: 296


Found one Java-level deadlock:
=============================
"http-nio-8889-exec-34":
  waiting to lock monitor 0x00007fe2c45001d8 (object 0x0000000086bef5e8, a com.hfy.service.impl.SessionServiceImpl),
  which is held by "SockJS-1"
"SockJS-1":
  waiting to lock monitor 0x00007fe2d424ec98 (object 0x0000000086bef5c8, a com.hfy.service.impl.TokenServiceImpl),
  which is held by "SockJS-2"
"SockJS-2":
  waiting to lock monitor 0x00007fe2c45001d8 (object 0x0000000086bef5e8, a com.hfy.service.impl.SessionServiceImpl),
  which is held by "SockJS-1"

Java stack information for the threads listed above:
===================================================
"http-nio-8889-exec-34":
	at com.hfy.service.impl.SessionServiceImpl.keepAlive(SessionServiceImpl.java:114)
	- waiting to lock <0x0000000086bef5e8> (a com.hfy.service.impl.SessionServiceImpl)
	at com.hfy.PmWebSocketHandler.handleTextMessage(PmWebSocketHandler.java:85)
	- locked <0x00000000d8ca01c8> (a org.springframework.web.socket.adapter.standard.StandardWebSocketSession)
	............
"SockJS-1":
	at com.hfy.service.impl.TokenServiceImpl.deleteToken(TokenServiceImpl.java:49)
	- waiting to lock <0x0000000086bef5c8> (a com.hfy.service.impl.TokenServiceImpl)
	............
	at com.hfy.service.impl.SessionServiceImpl.sessionTimeout(SessionServiceImpl.java:96)
	- locked <0x0000000086bef5e8> (a com.hfy.service.impl.SessionServiceImpl)
	at com.hfy.service.ScheduleTask.sessionTimeout(ScheduleTask.java:75)
	.......
"SockJS-2":
	at com.hfy.service.impl.SessionServiceImpl.deleteSession(SessionServiceImpl.java:47)
	- waiting to lock <0x0000000086bef5e8> (a com.hfy.service.impl.SessionServiceImpl)
	............
	at com.hfy.service.impl.TokenServiceImpl.tokenTimeout(TokenServiceImpl.java:80)
	- locked <0x0000000086bef5c8> (a com.hfy.service.impl.TokenServiceImpl)
	at com.hfy.service.ScheduleTask.tokenTimeout(ScheduleTask.java:69)
	.......

Found 1 deadlock.

可以很清楚的看到：
　　“SockJS-2”:
　　TokenServiceImpl.java:80执行tokenTimeout()的时候，获得了锁<0x0000000086bef5c8>,方法执行到了SessionServiceImpl.java:47,执行deleteSession时，等待锁<0x0000000086bef5e8>
　　“SockJS-1”:
　　SessionServiceImpl.java:96执行sessionTimeout()的时候，获得了锁<0x0000000086bef5e8>,方法执行到了TokenServiceImpl.java:49，执行deleteToken时，等待锁<0x0000000086bef5c8>
　　典型的死锁，知道问题所在，解决去了。。。。。。

Tomcat一个BUG造成CLOSE_WAIT

此问题还未遇见
http://cxytiandi.com/blog/detail/11147
http://www.cnblogs.com/saaav/p/6258831.html