Java thread dump的分析思路

编程语言 2018-05-13 21:44:40 阅读次数: 0
Java thread dump的分析思路：
第一步：java thread dump中首先需要检查是否有死锁，即deadlock，通过jstack生成的dump，
会自动将deadlock列出来；如果有deadlock，需要查看引起死锁的代码；

第二步：检查是否有条件等待状态的线程【wait on condition】，如果有，需要检查对应代码的业务逻辑是否合理！

第三步：其次要检查是否大量线程发生block，一般blocked thread的状态有【waiting for monitor entry】和【in Object.wait()】
前者是在Entry Set队列中，【in Object.wait()】是在Wait Set队列中。

第四步：检查是否发生热锁，发生热锁的必要条件是：
（1）、cpu繁忙并且系统态远大于用户态
（2）、cpu数目越多，性能反而越差，可以通过taskset指定引用哪些cpu核。
如果发生热锁，需要定位到代码段，分析其代码逻辑并进行改进。


注意：1、在分析thread dump时，要比对至少三次的thread dump，而不要拿某一个dump来说事，因为thread dump是某个时刻的快照
，需要横向向比对定位问题。2、NIO比BIO在多线程处理上更好一些。3、代码中尽量少用synchronized关键字，除非你对多线程管理的很好。

一般线程的状态有以下几种：
************************
1.线程状态：【runnable】
"Running HTTPHandler-995" prio=10 tid=0x2eff0800 nid=0x108a runnable [0x7c75e000]
   java.lang.Thread.State: RUNNABLE
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream.java:146)
at java.io.BufferedInputStream.fill(BufferedInputStream.java:235)
at java.io.BufferedInputStream.read1(BufferedInputStream.java:275)
at java.io.BufferedInputStream.read(BufferedInputStream.java:334)
- locked <0x50724c18> (a java.io.BufferedInputStream)
at com.cnd.web.http.tcp.TCP_BIOProtocol.readLine(Unknown Source)
at com.cnd.web.http.tcp.TCP_BIOProtocol.readRequestLine(Unknown Source)
at com.cnd.web.http.tcp.TCP_BIOProtocol.read(Unknown Source)
at com.cnd.web.http.tcp.TCP_BIOConnection.getNextRequest(Unknown Source)
at com.cnd.web.http.ConnectionHandler.processConnection(Unknown Source)
at com.cnd.web.http.ConnectionHandler.run(Unknown Source)
at com.cnd.util.ThreadPoolImpl$WorkerThread.run(Unknown Source)
************************
2.线程状态：【wait on condition】

*************************
3.线程状态：【waiting for monitor entry】
"Running ORBWorker-299" prio=10 tid=0x2ea82400 nid=0x10a3 waiting for monitor entry [0x7cc2c000]
   java.lang.Thread.State: BLOCKED (on object monitor)
at com.cnd.corba.ee.impl.orb.ORBImpl.create_any(Unknown Source)
- locked <0x4632e838> (a com.cnd.corba.ee.impl.orb.ORBImpl)
at com.cnd.corba.ee.impl.javax.rmi.CORBA.Util.writeAny(Unknown Source)
at com.cnd.corba.rmi.Util.writeAny(Unknown Source)
at javax.rmi.CORBA.Util.writeAny(Util.java:96)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.writeObjectField(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.writeField(Unknown Source)
at com.cnd.corba.ee.impl.io.OutputStreamHook$HookPutFields.write(Unknown Source)
at com.cnd.corba.ee.impl.io.OutputStreamHook.writeFields(Unknown Source)
at java.beans.PropertyChangeSupport.writeObject(PropertyChangeSupport.java:418)
at sun.reflect.GeneratedMethodAccessor23.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.invokeObjectWriter(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.outputObject(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.simpleWriteObject(Unknown Source)
at com.cnd.corba.ee.impl.io.ValueHandlerImpl.writeValueInternal(Unknown Source)
at com.cnd.corba.ee.impl.io.ValueHandlerImpl.writeValueWithVersion(Unknown Source)
at com.cnd.corba.ee.impl.io.ValueHandlerImpl.writeValue(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.writeRMIIIOPValueType(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.write_value(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.write_value(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.write_value(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream.write_value(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.writeObjectField(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.outputClassFields(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.defaultWriteObjectDelegate(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.outputObject(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.simpleWriteObject(Unknown Source)
at com.cnd.corba.ee.impl.io.ValueHandlerImpl.writeValueInternal(Unknown Source)
at com.cnd.corba.ee.impl.io.ValueHandlerImpl.writeValueWithVersion(Unknown Source)
at com.cnd.corba.ee.impl.io.ValueHandlerImpl.writeValue(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.writeRMIIIOPValueType(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.write_value(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.write_value(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.write_abstract_interface(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream.write_abstract_interface(Unknown Source)
at com.cnd.corba.ee.impl.javax.rmi.CORBA.Util.writeAbstractObject(Unknown Source)
at com.cnd.corba.rmi.Util.writeAbstractObject(Unknown Source)
at javax.rmi.CORBA.Util.writeAbstractObject(Util.java:147)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.writeObjectOverride(Unknown Source)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:339)
at java.util.ArrayList.writeObject(ArrayList.java:673)
at sun.reflect.GeneratedMethodAccessor43.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.invokeObjectWriter(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.outputObject(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.simpleWriteObject(Unknown Source)
at com.cnd.corba.ee.impl.io.ValueHandlerImpl.writeValueInternal(Unknown Source)
at com.cnd.corba.ee.impl.io.ValueHandlerImpl.writeValueWithVersion(Unknown Source)
at com.cnd.corba.ee.impl.io.ValueHandlerImpl.writeValue(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.writeRMIIIOPValueType(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.write_value(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.write_value(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.write_value(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream.write_value(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.writeObjectField(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.outputClassFields(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.defaultWriteObjectDelegate(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.outputObject(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.simpleWriteObject(Unknown Source)
at com.cnd.corba.ee.impl.io.ValueHandlerImpl.writeValueInternal(Unknown Source)
at com.cnd.corba.ee.impl.io.ValueHandlerImpl.writeValueWithVersion(Unknown Source)
at com.cnd.corba.ee.impl.io.ValueHandlerImpl.writeValue(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.writeRMIIIOPValueType(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.write_value(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.write_value(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream.write_value(Unknown Source)
at com.cnd.corba.ee.impl.corba.TCUtility.marshalIn(Unknown Source)
at com.cnd.corba.ee.impl.corba.AnyImpl.write_value(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.write_any(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream.write_any(Unknown Source)
at com.cnd.corba.ee.impl.javax.rmi.CORBA.Util.writeAny(Unknown Source)
at com.cnd.corba.rmi.Util.writeAny(Unknown Source)
at javax.rmi.CORBA.Util.writeAny(Util.java:96)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.writeObjectField(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.outputClassFields(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.defaultWriteObjectDelegate(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.outputObject(Unknown Source)
at com.cnd.corba.ee.impl.io.IIOPOutputStream.simpleWriteObject(Unknown Source)
at com.cnd.corba.ee.impl.io.ValueHandlerImpl.writeValueInternal(Unknown Source)
at com.cnd.corba.ee.impl.io.ValueHandlerImpl.writeValueWithVersion(Unknown Source)
at com.cnd.corba.ee.impl.io.ValueHandlerImpl.writeValue(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.writeRMIIIOPValueType(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.write_value(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.write_value(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream_1_0.write_value(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputStream.write_value(Unknown Source)
at com.cssnet.platform.baseframe.core.facade._DomainFacadeBean_ObjectImpl_2_Tie._invoke(Unknown Source)
at com.cnd.corba.ee.impl.protocol.CorbaServerRequestDispatcherImpl.dispatchToServant(Unknown Source)
at com.cnd.corba.ee.impl.protocol.CorbaServerRequestDispatcherImpl.dispatch(Unknown Source)
at com.cnd.corba.ee.impl.protocol.CorbaMessageMediatorImpl.handleRequestRequest(Unknown Source)
at com.cnd.corba.ee.impl.protocol.CorbaMessageMediatorImpl.handleRequest(Unknown Source)
at com.cnd.corba.ee.impl.protocol.CorbaMessageMediatorImpl.handleInput(Unknown Source)
at com.cnd.corba.ee.impl.protocol.giopmsgheaders.RequestMessage_1_2.callback(Unknown Source)
at com.cnd.corba.ee.impl.protocol.CorbaMessageMediatorImpl.handleRequest(Unknown Source)
at com.cnd.corba.ee.impl.transport.SocketOrChannelConnectionImpl.dispatch(Unknown Source)
at com.cnd.corba.ee.impl.transport.SocketOrChannelConnectionImpl.read(Unknown Source)
at com.cnd.corba.ee.impl.transport.ReaderThreadImpl.doWork(Unknown Source)
at com.cnd.corba.plugin.ee.ThreadPoolImpl$WorkAdapter.run(Unknown Source)
at com.cnd.util.ThreadPoolImpl$WorkerThread.run(Unknown Source)
************************
4.线程状态：【in Object.wait()】
"Running ORBWorker-282" prio=10 tid=0x2f194800 nid=0x107c in Object.wait() [0x7c4ee000]
   java.lang.Thread.State: BLOCKED (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x46b47480> (a java.lang.Object)
at com.cnd.corba.ee.impl.transport.SocketOrChannelConnectionImpl.writeLock(Unknown Source)
- locked <0x46b47480> (a java.lang.Object)
at com.cnd.corba.ee.impl.encoding.BufferManagerWriteStream.sendFragment(Unknown Source)
at com.cnd.corba.ee.impl.encoding.BufferManagerWriteStream.sendMessage(Unknown Source)
at com.cnd.corba.ee.impl.encoding.CDROutputObject.finishSendingMessage(Unknown Source)
at com.cnd.corba.ee.impl.protocol.CorbaMessageMediatorImpl.sendResponse(Unknown Source)
at com.cnd.corba.ee.impl.protocol.CorbaMessageMediatorImpl.handleRequest(Unknown Source)
at com.cnd.corba.ee.impl.protocol.CorbaMessageMediatorImpl.handleInput(Unknown Source)
at com.cnd.corba.ee.impl.protocol.giopmsgheaders.RequestMessage_1_2.callback(Unknown Source)
at com.cnd.corba.ee.impl.protocol.CorbaMessageMediatorImpl.handleRequest(Unknown Source)
at com.cnd.corba.ee.impl.transport.SocketOrChannelConnectionImpl.dispatch(Unknown Source)
at com.cnd.corba.ee.impl.transport.SocketOrChannelConnectionImpl.read(Unknown Source)
at com.cnd.corba.ee.impl.transport.ReaderThreadImpl.doWork(Unknown Source)
at com.cnd.corba.plugin.ee.ThreadPoolImpl$WorkAdapter.run(Unknown Source)
at com.cnd.util.ThreadPoolImpl$WorkerThread.run(Unknown Source)
***********************************
【注意】线程的6种状态：New => Runnable => Terminated => Waiting ||  Timed_wating || Blocked，死锁不是线程的状态。

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