debug on gpu node

Debugging on a Specialized GPU Node with VS Code

In this post, we’ll explore how to connect to a GPU node on a cluster server via SSH in Visual Studio Code (VS Code) and debug a Python file in that environment.

Prerequisites

You should already be able to connect to the login node on VS Code.

Strategy

The strategy involves logging in and applying for a compute-node with a GPU, setting a configuration for that GPU node in your .ssh/config with a ProxyJump through the login node, and finally logging into the GPU node via remote-SSH in VS Code. You can find more details on this approach on Stack Overflow .

Preliminary Work

Before proceeding, ensure your local public key is added to the SSH on the login node. Direct SSH to the GPU node should work seamlessly without requiring a password.

Local SSH Config File Setup

Here’s what your local .ssh/config file should look like:

#example
Host gateway
  HostName 192.168.1.1
  User gateway_user

Host Jumpmachine
  HostName example.domain.com
  Port 22
  User jump_user
  HostkeyAlgorithms ssh-dss,ssh-rsa
  KexAlgorithms +diffie-hellman-group1-sha1

# Configuration for the Login Node
Host loginnode
  HostName 192.168.1.1(example)
  User 21481350
  Port 22
  ProxyJump Jumpmachine

# Configuration for the Compute Node
Host computenode
# HostName here is the internal name or IP you use to access the compute node through SSH
  HostName gpunode
  User compute_user
  ProxyJump loginnode

After setting this up, refresh your VS Code SSH and select ‘computenode’ to open a server session where you can happily debug.

Potential Difficulties

Difficulty 1: Connection Failures

Even though you can connect via command-line SSH to computenode, connecting through VS Code might fail. This could be due to a version conflict in VS Code or its extensions.

Solution:

1. Attempt to connect via command line and manually clear the VS Code server on the compute node:

   ssh computenode
   cd .vscode-server/
   rm -rf *
   ps -ef | grep vscode
   kill -9 [process_ids]  # Replace [process_ids] with the actual IDs shown
   cd ..
   rm -rf .vscode-server/
   ps -ef | grep vscode
   kill -9 [process_ids]

2. After cleaning up, download and try using a different version of VS Code. Make sure to remove the old server files and let VS Code reinstall the server component.

Difficulty 2: Debugging Errors

When you attempt to debug using F5, errors might pop up indicating missing plugins or interpreters, suggesting a version mismatch.

For similar experiences, see this CSDN blog post .

Solution:
If you connect successfully but encounter issues when hitting F5 to debug, it could be another version issue. The solution is similar: switch to another version of VS Code after cleaning up old server files. Also, be mindful of any network or proxy issues that could be interfering.

Other remainders

Viewing Mac Public Key

If you need to verify your public key on a Mac, you can use the following commands:

cd ~/.ssh
ls
cat id_rsa.pub

Copy and paste your public key into the server’s .ssh/authorized_keys file to enable password-less SSH access.

Issues with VPN

Switching VPN connections can lead to connectivity problems in VS Code. To troubleshoot, you may need to:

ps -ef | grep vscode
kill -9 [process_id]  # Replace [process_id] with the actual IDs

After clearing any potentially hanging processes, try reconnecting to the compute node using VS Code. If problems persist, verify your VPN settings and network configuration to ensure they are compatible with your remote access requirements. Adjusting the VPN settings or temporarily disabling the VPN might help identify whether it is the source of the connection issues.

Alternative Approaches: Caution Advised

While exploring remote development setups, I came across an approach that involves modifying JSON configurations (see GitHub issue ). However, I encountered similar problems as discussed in the issue and ultimately found the method unreliable.

Recommendation:

Due to the complexities and unresolved issues noted in the GitHub discussion, I recommend avoiding this JSON configuration approach for setting up remote environments in VS Code. Stick with proven SSH configurations for a more stable setup.

Additional Resources and Troubleshooting

• CSDN blog

conclusion

Changing the version until everything is feasible….