error writing command

[giaschweitzer]

I am getting this error and cannot seem to understand what it means.
"HYD_sock_write (..\windows\src\hydra_sock.c:382): write error (errno = 34) error writing command"

[rmcdermo]

We need more information to diagnose the problem. How are you running your case? Can you post the input file? Based on the snippet of information you have given us, this is what AI says:

The error you're seeing:

HYD_sock_write (..\windows\src\hydra_sock.c:382): write error (errno = 34) error writing command

is coming from the Hydra process manager, which is part of the MPICH or Intel MPI infrastructure. It usually means there's a communication issue between MPI processes, and in this specific case, errno = 34 is key.

Interpretation of errno = 34:

On most systems, errno 34 corresponds to ERANGE — "Result too large", though this may vary slightly depending on the platform.

Possible Causes

Here are a few reasons you might see this error:

1. Incorrect buffer size or data too large:

   • You're sending data that's too large to fit in the socket buffer.
   • Could happen if you're doing custom socket programming or passing large messages in MPI.

2. Mismatch between MPI versions or compilers:

   • Mixing incompatible MPI builds (e.g., compiling with OpenMPI and running with MPICH).

3. Running Windows binaries on non-Windows system or vice versa:

   • The path in the error ..\windows\src\hydra_sock.c suggests a Windows-specific build. If you're running a cross-compiled binary or under WSL, that could cause issues.

4. Faulty or misconfigured MPI installation:

   • If HYDRA is broken or misconfigured, it may not be able to manage communication properly.

5. Permissions or Antivirus issues (on Windows):

   • Windows firewall or antivirus may be interfering with socket communication between MPI processes.

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Fix Suggestions

Here are a few things to try depending on your setup:

✅ Check your MPI setup:

• What MPI distribution are you using? (MPICH, Intel MPI, MS-MPI?)
• Make sure mpicc and mpirun come from the same MPI install.

✅ Recompile with matching compiler and MPI:

• Make sure you're using the same compiler that your MPI was built with.
• Clean and rebuild everything to ensure ABI compatibility.

✅ Use smaller message sizes (if applicable):

• If you're sending large messages via MPI, try breaking them into smaller chunks.

✅ Run a simple MPI test:

Try this minimal test:

#include <mpi.h>
#include <stdio.h>

int main(int argc, char **argv) {
    MPI_Init(&argc, &argv);
    int rank;
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    printf("Hello from rank %d\n", rank);
    MPI_Finalize();
    return 0;
}

Then run with:

mpicc test.c -o test
mpirun -np 2 ./test

See if the error still occurs. If it does, it's a system-level or installation problem.

✅ If using WSL:

If you're on Windows Subsystem for Linux (WSL), MPI over sockets sometimes fails due to networking limitations. Try updating to WSL2 or using a native Linux or Windows build of MPI.

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If you can tell me:

• What system you’re on (Windows, Linux, WSL, etc.)
• What MPI you’re using
• How you’re running your job

…I can tailor the fix more specifically.