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
我不明白这意味着什么，
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();
}
}
导致错误的原因是什么？如何解决？
EDITTTTT
将minlength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
好的，经过一些试验和错误后，我在第19行注释掉'// len * = 2）'，注释掉了，程序会运行，但它会持续运行2个字节，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，但是如何解决这个问题？
答案 0 :(得分：0)
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你的Recv()电话（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);
所以“count”（len）小于长度（即2）。您将minlen设置为1（与评论所说的不是“2”），请尝试将其设置为2。
答案 1 :(得分：0)
您的代码的主要问题是您错过了一个内部循环，该循环在使用i=0的过程中从MAX_LOOP运行到rank=1。由于外部循环的长度不同，因此使用rank=0的流程正在发送len=2的消息，而rank=1的进程期望带有len=4的消息，因为它处于下一个外循环迭代中。如果插入print语句，您将看到第一条消息已成功完成。但是对于第二次迭代，它是一个未命中的长度匹配。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);
}
}
}