我已经使用过Samurai，我可以看到没有死锁和几个线程在等待，但我似乎无法弄清楚究竟是哪个锁停止了这个过程。谁能帮我吗？
我不是在寻找人们猜测我的问题是什么，更多关于如何改变代码以便更容易追踪问题的建议。我通过我的第一次发送和接收然后程序停止它应该发送第二条消息。我是多线程的新手，这是我第一次拉jstack
2013-04-02 23:43:12
Full thread dump OpenJDK Zero VM (22.0-b10 mixed mode):
"Attach Listener" daemon prio=10 tid=0x0037c880 nid=0x105b waiting on condition [0x00000000]
java.lang.Thread.State: RUNNABLE
"Thread-3" prio=10 tid=0x0037c488 nid=0x1041 waiting on condition [0xa7ddd000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0xab770958> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2043)
at org.dnsdojo.ryanhost.GA.MuPlusOne.RobotInterface.evaluate(RobotInterface.java:38)
at org.dnsdojo.ryanhost.GA.MuPlusOne.RobotInterface.run(RobotInterface.java:69)
at java.lang.Thread.run(Thread.java:722)
"Thread-1" prio=10 tid=0x0036ff10 nid=0x1036 waiting on condition [0xa7f5d000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0xab770940> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2043)
at org.dnsdojo.ryanhost.GA.MuPlusOne.TwoWaySerialCommTest$SerialWriter.run(TwoWaySerialCommTest.java:229)
at java.lang.Thread.run(Thread.java:722)
"Thread-0" daemon prio=10 tid=0x0036a1e8 nid=0x1035 runnable [0xa80dd000]
java.lang.Thread.State: RUNNABLE
at gnu.io.RXTXPort.eventLoop(Native Method)
at gnu.io.RXTXPort$MonitorThread.run(RXTXPort.java:1644)
"Service Thread" daemon prio=10 tid=0x00253440 nid=0x102b runnable [0x00000000]
java.lang.Thread.State: RUNNABLE
"Signal Dispatcher" daemon prio=10 tid=0x00251988 nid=0x102a runnable [0x00000000]
java.lang.Thread.State: RUNNABLE
"Finalizer" daemon prio=10 tid=0x0020c880 nid=0x1029 in Object.wait() [0xa8ac1000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0xab718a88> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:135)
- locked <0xab718a88> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:151)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:177)
"Reference Handler" daemon prio=10 tid=0x00209f18 nid=0x1028 in Object.wait() [0xa8c41000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0xab718b10> (a java.lang.ref.Reference$Lock)
at java.lang.Object.wait(Object.java:503)
at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:133)
- locked <0xab718b10> (a java.lang.ref.Reference$Lock)
"main" prio=10 tid=0x00180fa8 nid=0x1022 in Object.wait() [0xb6848000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0xa90716a8> (a org.dnsdojo.ryanhost.GA.MuPlusOne.CandidateTest)
at java.lang.Object.wait(Object.java:503)
at org.dnsdojo.ryanhost.GA.MuPlusOne.MuPlusOneAlgorithm.runOnBot(MuPlusOneAlgorithm.java:120)
- locked <0xa90716a8> (a org.dnsdojo.ryanhost.GA.MuPlusOne.CandidateTest)
at org.dnsdojo.ryanhost.GA.MuPlusOne.MuPlusOneAlgorithm.initialFitness(MuPlusOneAlgorithm.java:72)
- locked <0xab718bd0> (a org.dnsdojo.ryanhost.GA.MuPlusOne.MuPlusOneAlgorithm)
at org.dnsdojo.ryanhost.GA.MuPlusOne.MuPlusOneAlgorithm.main(MuPlusOneAlgorithm.java:138)
"VM Thread" prio=10 tid=0x00204910 nid=0x1027 runnable
"VM Periodic Task Thread" prio=10 tid=0x00255130 nid=0x102c waiting on condition
JNI global references: 36
按要求添加代码 串行通信类
package org.dnsdojo.ryanhost.GA.MuPlusOne;
import gnu.io.CommPort;
import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent;
import gnu.io.SerialPortEventListener;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/**
* This version of the TwoWaySerialComm example makes use of the
* SerialPortEventListener to avoid polling.
*
*/
public class TwoWaySerialComm
{
public TwoWaySerialComm()
{
super();
}
void connect ( String portName ) throws Exception
{
listPorts();
CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier(portName);
if ( portIdentifier.isCurrentlyOwned() )
{
System.out.println("Error: Port is currently in use");
}
else
{
CommPort commPort = portIdentifier.open(this.getClass().getName(),2000);
if ( commPort instanceof SerialPort )
{
SerialPort serialPort = (SerialPort) commPort;
serialPort.setSerialPortParams(57600,SerialPort.DATABITS_8,SerialPort.STOPBITS_1,SerialPort.PARITY_NONE);
InputStream in = serialPort.getInputStream();
OutputStream out = serialPort.getOutputStream();
(new Thread(new SerialWriter(out))).start();
serialPort.addEventListener(new SerialReader(in));
serialPort.notifyOnDataAvailable(true);
}
else
{
System.out.println("Error: Only serial ports are handled by this example.");
}
}
}
static void listPorts()
{
java.util.Enumeration<CommPortIdentifier> portEnum = CommPortIdentifier.getPortIdentifiers();
while(portEnum.hasMoreElements())
{
CommPortIdentifier portIdentifier = portEnum.nextElement();
if(portIdentifier == null)
{
System.out.println("No ports");
}
System.out.println("Available - " + portIdentifier.getName());
}
}
/**
* Handles the input coming from the serial port. A new line character
* is treated as the end of a block in this example.
*/
public static class SerialReader implements SerialPortEventListener
{
private InputStream in;
private byte[] buffer = new byte[1024];
public SerialReader ( InputStream in )
{
this.in = in;
}
public void serialEvent(SerialPortEvent arg0) {
int data;
try
{
int len = 0;
while ( ( data = in.read()) > -1 )
{
if ( data == '\n' ) {
break;
}
buffer[len++] = (byte) data;
}
System.out.print(new String(buffer,0,len));
}
catch ( IOException e )
{
e.printStackTrace();
System.exit(-1);
}
}
}
/** */
public static class SerialWriter implements Runnable
{
OutputStream out;
public SerialWriter ( OutputStream out )
{
this.out = out;
}
public void run ()
{
try
{
int c = 0;
while ( ( c = System.in.read()) > -1 )
{
this.out.write(c);
}
}
catch ( IOException e )
{
e.printStackTrace();
System.exit(-1);
}
}
}
public static void main ( String[] args )
{
try
{
(new TwoWaySerialComm()).connect("/dev/ttyS82");
}
catch ( Exception e )
{
TwoWaySerialComm.listPorts();
e.printStackTrace();
}
}
}
RobotInterface类
package org.dnsdojo.ryanhost.GA.MuPlusOne;
import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;
public class RobotInterface implements Runnable
{
// create a serial connection
// transmit a string and check for response
// wait for evaluation
// take evaluation
private CandidateTest candidate;
private TwoWaySerialCommTest serialConnection;
//private Random rng = new Random();
protected static Logger logger = Logger.getLogger("Thread" + Thread.currentThread().getName());
public RobotInterface(CandidateTest test, TwoWaySerialCommTest serialConnection)
{
this.candidate = test;
this.serialConnection = serialConnection;
PropertyConfigurator.configure("log4j.properties");
}
public void evaluate (Genome genome)
{
//send to robot and return fitness
//genome.setFitness(rng.nextDouble());
logger.debug("fitness is " + genome.getFitness());
try
{
String s = candidate.getCandidate().toString();
System.out.println(s);
TwoWaySerialCommTest.lock.lock();
System.out.println(s);
serialConnection.put(s);
TwoWaySerialCommTest.inputAvailable.await();
try
{
candidate.getCandidate().setFitness(Float.parseFloat(serialConnection.take()));
}
catch(Exception e)
{
e.printStackTrace();
}
}
catch ( Exception e )
{
TwoWaySerialCommTest.listPorts();
e.printStackTrace();
}
finally
{
TwoWaySerialCommTest.lock.unlock();
}
}
public void run()
{
logger.debug("entering run of Robot Interface");
logger.debug("Send Genome via serial and wait for a response");
Genome testSubject = candidate.getCandidate();
evaluate(testSubject);
candidate.finished();
}
}
总结执行 - 我有一个for循环，它创建RobotInterface线程，每个线程包含一个包含位串的Genome。这个基因组参考保存在candidateTest中，该候选测试只是RobotInterface的一个共享类，以及完成时发出信号的调用线程。
使用TwoWaySerialCommTest，RobotInterface将bitstring字符串发送给机器人。机器人对其进行求值并返回一个适应函数，该函数由SerialReader解析为float。然后将下一个String发送给机器人。
在第一个字符串返回到机器人并且正在发送第二个字符串后发生锁定。我可以看到第一个String使它成为机器人，但第二个字符串没有。输出如下 -
initialFitness method
1101010101111111001100000101011100110000100001111111001000001001101101000011100101011000000100000000110110001110
5436 [main] DEBUG org.dnsdojo.ryanhost.GA.MuPlusOne.GeneticAlgorithm - Testing candidate
1101010101111111001100000101011100110000100001111111001000001001101101000011100101011000000100000000110110001110
1101010101111111001100000101011100110000100001111111001000001001101101000011100101011000000100000000110110001110
5853 [Thread-2] DEBUG Threadmain - entering run of Robot Interface
5869 [Thread-2] DEBUG Threadmain - Send Genome via serial and wait for a response
5881 [Thread-2] DEBUG Threadmain - fitness is 0.0
1101010101111111001100000101011100110000100001111111001000001001101101000011100101011000000100000000110110001110
1101010101111111001100000101011100110000100001111111001000001001101101000011100101011000000100000000110110001110
10
Output buffer after put
1101010101111111001100000101011100110000100001111111001000001001101101000011100101011000000100000000110110001110
Buffer isn't empty
initialFitness method
1110110101110000001100101100110001001010010101011110001101010010100100111011111000011101110000001110100111001111
16593 [main] DEBUG org.dnsdojo.ryanhost.GA.MuPlusOne.GeneticAlgorithm - Testing candidate
1110110101110000001100101100110001001010010101011110001101010010100100111011111000011101110000001110100111001111
1110110101110000001100101100110001001010010101011110001101010010100100111011111000011101110000001110100111001111
16944 [Thread-3] DEBUG Threadmain - entering run of Robot Interface
16953 [Thread-3] DEBUG Threadmain - Send Genome via serial and wait for a response
16964 [Thread-3] DEBUG Threadmain - fitness is 0.0
1110110101110000001100101100110001001010010101011110001101010010100100111011111000011101110000001110100111001111
1110110101110000001100101100110001001010010101011110001101010010100100111011111000011101110000001110100111001111
10
Output buffer after put
1110110101110000001100101100110001001010010101011110001101010010100100111011111000011101110000001110100111001111
Buffer isn't empty
答案 0 :(得分：2)
我的方法是消除明显不相关的线程。对你来说，这可能是
Attach Listener Service Thread Signal Dispatcher Finalizer Reference Handler VM Thread VM Periodic Task Thread 这些是VM托管的线程，即您没有显式或隐式创建它们。
留下Thread-x和Main个帖子。
查看堆栈跟踪，您可以根据您对代码的了解来推断出为什么是WAITING。例如，看起来队列正在等待满足Condition;
parking to wait for <0xab770958> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
Conditions被signal唤醒，因此您可能会想到为什么没有发送signal消息。由于此条件包含在队列实现中，因此问题不是您忘记调用signal。但是，你可能忘记打电话给它的东西呢？或无意中设置了永远不会满足条件的情况？
所以我会查看事件流，以确保锁定的任何内容都被解锁或任何会导致实时锁定的条件（请记住，JVM / samauri可以检测死锁但不能锁定活锁）。
这是我对如何解决它的一般想法。如果你想在某个地方发布代码，那么实际调试它/提供更多洞察人们可能会如何解决它是有帮助的。
祝你好运！