java - 我以前从未见过 MPJ Express 错误

Question

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

不明白什么意思

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();
    }
}

并且收到此错误:

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

好吧，经过一番尝试和错误后，我在第 19 行注释掉了 '//len *= 2)'，注释掉后，程序会运行，但它会持续以 2 个字节运行，并且不会停止在所需的 20 个循环之后，所以我认为这就是问题所在，但是如何解决这个问题？

Answer 1

您的异常似乎是由此 block of code: 引发的

  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+">");
    }

因此，count * numEls 似乎小于length。这一切似乎都会导致您的 Recv() 调用(我认为是第 29 行):

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

或

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

因此“计数”(len) 小于长度(即 2)。您将 minlen 设置为 1(不是像评论所说的“2”)，请尝试将其设置为 2。