我从未见过的 MPJ Express 错误答案

【问题标题】：MPJ Express error I have never seen before我从未见过的 MPJ Express 错误
【发布时间】：2013-04-06 07:39:31
【问题描述】：

我收到此运行时错误：

MPJ Express (0.35) is started in the cluster configuration
Starting process <0> on <Tornado>
Starting process <1> on <Predator>
mpi.MPIException: Error in SimplePacker : count <1> is less than length <2>
        at mpi.SimplePackerChar.unpack(SimplePackerChar.java:105)
        at mpi.Comm.recv(Comm.java:1305)
        at mpi.Comm.Recv(Comm.java:1255)
        at PingPongVariousLengths.main(PingPongVariousLengths.java:29)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at runtime.daemon.Wrapper.execute(Wrapper.java:165)
        at runtime.daemon.Wrapper.main(Wrapper.java:180)
java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at runtime.daemon.Wrapper.execute(Wrapper.java:165)
        at runtime.daemon.Wrapper.main(Wrapper.java:180)
Caused by: mpi.MPIException: mpi.MPIException: mpi.MPIException: Error in Simple
Packer : count <1> is less than length <2>
        at mpi.Comm.Recv(Comm.java:1259)
        at PingPongVariousLengths.main(PingPongVariousLengths.java:29)
        ... 6 more
Caused by: mpi.MPIException: mpi.MPIException: Error in SimplePacker : count <1>
 is less than length <2>
        at mpi.Comm.recv(Comm.java:1317)
        at mpi.Comm.Recv(Comm.java:1255)
        ... 7 more
Caused by: mpi.MPIException: Error in SimplePacker : count <1> is less than leng
th <2>
        at mpi.SimplePackerChar.unpack(SimplePackerChar.java:105)
        at mpi.Comm.recv(Comm.java:1305)
        ... 8 more

我不明白这是什么意思，

这是导致它的代码：

import mpi.* ;

class PingPongVariousLengths {

    static public void main(String[] args) {

        MPI.Init(args);
        int myrank = MPI.COMM_WORLD.Rank();
        int tag = 99;
        int maxlen = 104857600; //200 megabytes     104857600 characters * 2 bytes per character = 209715200 bytes total, or 200 megabytes
        int minlen = 1; // 2 bytes
        char [] sendbuff = new char [maxlen];
        char [] recvbuff = new char [maxlen];
        long speedKbps;
        long speedMbps;
        long durationseconds;
int MAX_LOOPS = 20;

for (int len = minlen; len <= maxlen; len *= 2) {
        if (myrank == 0) {
                durationseconds = 0;
                for (int i = 0; i < MAX_LOOPS; i++) {
                        long startTime = System.nanoTime();           
                        MPI.COMM_WORLD.Send(sendbuff, 0, len, MPI.CHAR, 1, tag);
                        MPI.COMM_WORLD.Recv(recvbuff, 0, len, MPI.CHAR, 1, tag);
                        long endTime = System.nanoTime();
                        long duration = endTime - startTime;
                        durationseconds = durationseconds + (duration* 10-9);
                }
                durationseconds = durationseconds / MAX_LOOPS;
                System.out.println("Average time for the ping to be sent and recived of " + (len*2) + " bytes is " + durationseconds + " seconds");
                double transferRateMb = ((len*524288.0) / durationseconds );
                System.out.println("average transferRate (megabytes) : " + transferRateMb + " megabytes per second");
        } else if (myrank == 1) {
                MPI.COMM_WORLD.Recv(recvbuff, 0, len, MPI.CHAR, 0, tag);
                MPI.COMM_WORLD.Send(recvbuff, 0, len, MPI.CHAR, 0, tag);
        }
}

        MPI.Finalize();
    }
}

导致错误的原因以及如何解决？

编辑TTTT

将最小长度更改为 2

import mpi.* ;

class PingPongVariousLengths {

    static public void main(String[] args) {

        MPI.Init(args);
        int myrank = MPI.COMM_WORLD.Rank();
        int tag = 99;
        int maxlen = 104857600; //200 megabytes     104857600 characters * 2 bytes per character = 209715200 bytes total, or 200 megabytes
        int minlen = 2; // 2 bytes
        char [] sendbuff = new char [maxlen];
        char [] recvbuff = new char [maxlen];
        long speedKbps;
        long speedMbps;
        long durationseconds;
int MAX_LOOPS = 20;

for (int len = minlen; len <= maxlen; len *= 2) {//len=*2 doubles the ping size each time
        if (myrank == 0) {
                durationseconds = 0;
                for (int i = 0; i < MAX_LOOPS; i++) {
                        long startTime = System.nanoTime();           
                        MPI.COMM_WORLD.Send(sendbuff, 0, len, MPI.CHAR, 1, tag);
                        MPI.COMM_WORLD.Recv(recvbuff, 0, len, MPI.CHAR, 1, tag);
                        long endTime = System.nanoTime();
                        long duration = endTime - startTime;
                        durationseconds = durationseconds + (duration* 10-9);// Converts nanoseconds to seconds
                }
                durationseconds = durationseconds / MAX_LOOPS;
                 //double transferRate = ((len*2.0) / durationseconds ) ; //amount of data in bytes transferred in 1 second. Currently returning 0 for every result
                //System.out.println("transferRate: " + transferRate + " bytes per second");
                System.out.println("Average time for the ping to be sent and recived of " + (len*2) + " bytes is " + durationseconds + " seconds");
                double transferRateMb = ((len*524288.0) / durationseconds );
                System.out.println("average transferRate (megabytes) : " + transferRateMb + " megabytes per second");
        } else if (myrank == 1) {
                MPI.COMM_WORLD.Recv(recvbuff, 0, len, MPI.CHAR, 0, tag);
                MPI.COMM_WORLD.Send(recvbuff, 0, len, MPI.CHAR, 0, tag);
        }
}

        MPI.Finalize();
    }
}

我得到了这个错误：

PongVariousLengths
MPJ Express (0.35) is started in the cluster configuration
Starting process <0> on <Tornado>
Starting process <1> on <Predator>
mpi.MPIException: Error in SimplePacker : count <2> is less than length <4>
        at mpi.SimplePackerChar.unpack(SimplePackerChar.java:105)
        at mpi.Comm.recv(Comm.java:1305)
        at mpi.Comm.Recv(Comm.java:1255)
        at PingPongVariousLengths.main(PingPongVariousLengths.java:25)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at runtime.daemon.Wrapper.execute(Wrapper.java:165)
        at runtime.daemon.Wrapper.main(Wrapper.java:180)
java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at runtime.daemon.Wrapper.execute(Wrapper.java:165)
        at runtime.daemon.Wrapper.main(Wrapper.java:180)
Caused by: mpi.MPIException: mpi.MPIException: mpi.MPIException: Error in Simple
Packer : count <2> is less than length <4>
        at mpi.Comm.Recv(Comm.java:1259)
        at PingPongVariousLengths.main(PingPongVariousLengths.java:25)
        ... 6 more
Caused by: mpi.MPIException: mpi.MPIException: Error in SimplePacker : count <2>
 is less than length <4>
        at mpi.Comm.recv(Comm.java:1317)
        at mpi.Comm.Recv(Comm.java:1255)
        ... 7 more
Caused by: mpi.MPIException: Error in SimplePacker : count <2> is less than leng
th <4>
        at mpi.SimplePackerChar.unpack(SimplePackerChar.java:105)
        at mpi.Comm.recv(Comm.java:1305)
        ... 8 more

编辑 2

好的，经过一番反复试验，我在第 19 行注释掉了 '//len *= 2)'，注释掉后，程序会运行，但它会一直以 2 个字节运行，并且没有停止在所需的 20 个循环之后，所以我认为这是问题所在，但是如何解决呢？

【问题讨论】：

只是符号 }
你不应该以minlen = 2开头。
我试过 minlen = 2，同样的错误，它是 1 因为 1 个字符是 2 个字节
@user2065929 错误说count 是1，如果你现在将count 传递为2，你怎么可能得到同样的错误。仔细检查您是否没有将1 作为count 传递到任何地方。
啊抱歉，我还以为你说的是别的，我没有改计数，现在试试

标签： java mpi

【解决方案1】：

这个block of code:似乎抛出了你的异常

  public void unpack(mpjbuf.Buffer mpjbuf, int length, Object buf,
                  int offset, int count) throws MPIException {

    if(count * numEls < length) {
      throw new MPIException ("Error in SimplePacker : count <"+
          (count*numEls)+"> is less than length <"+length+">");
    }

所以看来count * numEls 小于length。这一切似乎都导致了您的Recv() 电话（我假设是第29 行），要么：

MPI.COMM_WORLD.Recv(recvbuff, 0, len, MPI.CHAR, 1, tag);

或

MPI.COMM_WORLD.Recv(recvbuff, 0, len, MPI.CHAR, 0, tag);

所以“计数”（len）小于长度（即 2）。您已将 minlen 设置为 1（这不是 cmets 所说的“2”），请尝试将其设置为 2。

【讨论】：

即使在调整计数后他声称得到了同样的错误：>
将错误与当前代码一起添加到原始问题中
好的添加了另一个编辑，我想我已经找到了问题但不确定如何解决它

【解决方案2】：

您的代码的主要问题是您错过了在rank=1 的进程中从i=0 运行到MAX_LOOP 的内部循环。由于外部循环的长度不同，您的rank=0 进程正在发送len=2 的消息，而rank=1 的进程正在期待len=4 的消息，因为它在下一个外部循环迭代中。如果您插入打印语句，您将看到您的第一条消息已成功完成。但是对于第二次迭代，它的长度是不匹配的。这是代码修复：

for (int len = minlen; len <= maxlen; len *= 2) {
        if (myrank == 0) {
                durationseconds = 0;
                for (int i = 0; i < MAX_LOOPS; i++) {
                        long startTime = System.nanoTime();
                        System.out.println("Processor 0 printing len="+len);
                        MPI.COMM_WORLD.Send(sendbuff, 0, len, MPI.CHAR, 1, tag);
                        MPI.COMM_WORLD.Recv(recvbuff, 0, len, MPI.CHAR, 1, tag);
                        long endTime = System.nanoTime();
                        long duration = endTime - startTime;
                        durationseconds = durationseconds + (duration* 10-9);
                }
                durationseconds = durationseconds / MAX_LOOPS;
                System.out.println("Average time for the ping to be sent and recived of " + (len*2) + " bytes is " + durationseconds + " seconds");
                double transferRateMb = ((len*524288.0) / durationseconds );
                System.out.println("average transferRate (megabytes) : " + transferRateMb + " megabytes per second");
        } else if (myrank == 1) {
                for(int i =0; i < MAX_LOOPS; i++){
                        System.out.println("Processor 1 printing len="+len);
                        MPI.COMM_WORLD.Recv(recvbuff, 0, len, MPI.CHAR, 0, tag);
                        MPI.COMM_WORLD.Send(recvbuff, 0, len, MPI.CHAR, 0, tag);
                }
        }
}

【讨论】：