User blocked on main server - timeouts for requests

[prasadtalasila]

A user submitting an evaluation request gets blocked indefinitely under the following circumstances

1. User has a GitLab account
2. User submits the file (a.out) in this case but the file is not in the correct language directory. Infact, no language directory exists in the student's repo lab0. The repo has the following structure:

lab0
|-- a.out

3. Student submits the evaluation request

The main server now waits indefinitely for a response - however, the execution node doesn't crash.

Also, I tried to submit the evaluation request from a different device and it still blocks the user. I think instead of blocking the socket, the user is blocked in the implementation.

(Thanks to @rajat503 for bringing attention to this bug and for providing detailed bug report.

[prasadtalasila]

The problem is solved using timeouts for each of the pending requests.

[prasadtalasila]

Use a timeout of 3M for timing out for expiring all evaluation requests going from one autolab component to another. The autolab components that send evaluation requests are: browser-code, mainserver, and loadbalancer.

Timeouts technique avoid deadlocks in the system.