运行时错误 java / mpi（除以零）

Question

我收到此运行时错误：

C:\Users\Richard\Dropbox\Year 3\DISPARP\Coursework>mpjrun -np 2 -dev niodev Ping
PongVariousLengths
MPJ Express (0.35) is started in the cluster configuration
Starting process <0> on <Tornado>
Starting process <1> on <Tornado>
Time for the ping to be sent and recived of 1 kb is 7 miliseconds
transferRate: 142.85714285714286KB per second
Speed of network in Mbps: 0
Time for the ping to be sent and recived of 2 kb is 0 miliseconds
transferRate: InfinityKB per second
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: java.lang.ArithmeticException: / by zero
        at PingPongVariousLengths.main(PingPongVariousLengths.java:32)
        ... 6 more

我认为是什么原因造成的，代码试图除以 0

Time for the ping to be sent and recived of 2 kb is 0 miliseconds
transferRate: InfinityKB per second

导致错误，我该如何解决这个错误，它仍然除以0但返回0而不是

如果您需要代码，请说:)

感谢您的帮助

编辑

代码：

if (myrank == 0) {
            for (int len = minlen; len <= maxlen; len *= 2) { //len=*2 doubles the ping size each time
                long startTime = System.currentTimeMillis();                    
                 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.currentTimeMillis();
                long duration = endTime - startTime;
                System.out.println("Time for the ping to be sent and recived of " + len + " kb is " + duration + " miliseconds");
                double transferRate = (len * 1000.0)/ duration ; //amount of data in kilobytes transferred in 1 second
                System.out.println("transferRate: " + transferRate + "KB per second");
                speedKbps = (len / duration);
                speedMbps = (speedKbps / 1024);
                System.out.println("Speed of network in Mbps: " + speedMbps);
                }
        } else if (myrank == 1) {
            for (int len = minlen; len <= maxlen; len *= 2) {
                 MPI.COMM_WORLD.Recv(recvbuff, 0, len, MPI.CHAR, 0, tag);
                 MPI.COMM_WORLD.Send(recvbuff, 0, len, MPI.CHAR, 0, tag);
            }
        }

Answer 1

尝试使用

long startTime = System.nanoTime();
... 
long endTime = System.nanoTime();

并调整 nanos 的所有计算。

如果它不起作用，只需在此处检查零

speedKbps = duration == 0 ? <big number here> : (len / duration);