Horovod Horovod fails with 'connection reset by peer'

What is Horovod Horovod fails with 'connection reset by peer'

Understanding Horovod

Horovod is an open-source distributed deep learning framework created by Uber. It is designed to make distributed deep learning fast and easy to use. Horovod achieves this by leveraging MPI (Message Passing Interface) and NCCL (NVIDIA Collective Communications Library) to efficiently scale training across multiple GPUs and nodes.

Identifying the Symptom

When using Horovod, you might encounter an error message stating: connection reset by peer. This error typically appears in the logs when a network connection between nodes is unexpectedly closed during the training process.

Exploring the Issue

The error connection reset by peer indicates that one of the nodes in the distributed setup has abruptly closed the connection. This can happen due to network instability, incorrect network configurations, or issues with the underlying hardware.

Network Instability

Network instability can cause intermittent connectivity issues, leading to unexpected connection resets. This is often the most common cause of this error.

Configuration Errors

Incorrect network configurations, such as firewall settings or incorrect IP addresses, can also lead to connection resets.

Steps to Fix the Issue

To resolve the connection reset by peer error, follow these steps:

Step 1: Check Network Stability

Ensure that the network is stable and that there are no interruptions. You can use tools like Wireshark to monitor network traffic and identify any anomalies.

Step 2: Verify Node Connectivity

Ensure that all nodes in the distributed setup are properly connected. Use the ping command to test connectivity between nodes:

ping [node-ip-address]

If any node is unreachable, check the network cables and switch configurations.

Step 3: Review Firewall Settings

Ensure that the firewall settings on each node allow traffic on the necessary ports. You can use the iptables command to list current rules:

sudo iptables -L

Adjust the rules to allow traffic on the ports used by Horovod.

Step 4: Check for Hardware Issues

Inspect the network hardware for any faults. Replace faulty cables or network cards as needed.

Conclusion

By following these steps, you should be able to resolve the connection reset by peer error in Horovod. Ensuring a stable network and correct configurations is key to successful distributed training. For more information, refer to the Horovod documentation.