saltstack / saltstack/salt

[Bug]: await_lock masks exceptions as FileLockError; minion job_queue requeues forever ("Failed to acquire job_queue lock" log flood)

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Description

What happened?

On 3007.13 two minions got stuck in an infinite requeue loop, logging ~180 lines/s of

[salt.minion :1960][WARNING ] Failed to acquire job_queue lock for jid 2026..., queuing anyway.

for a week, until /var/log/salt/minion reached 9 GB and filled /var. 59 stale jids cycled every 0.3 s. No job_queue.lock file existed, fds were 45/8192, plenty of RAM. The loop started 9 s after a Timeout encountered while sending ... _return request.

Root cause, two defects that combine:

  1. salt.utils.files.await_lock hides the real exception. The yield is inside the outer try, whose except Exception re-raises everything as FileLockError("Error encountered obtaining file lock ..."). Any exception raised by the async with await_lock(...) body is reported as a lock failure and its traceback is lost. In 3007.13 the body included _invoke_execution() and the proc-file write, so a job-start failure became "Failed to acquire job_queue lock". 3007.14 moved _invoke_execution out of the lock, but await_lock itself is unchanged in 3008.x, and the minion's except FileLockError handler still logs without the exception.

  2. The disk job queue has no exit. _process_process_queue_async_impl resubmits every queued_*.p file every 0.3 s (0.2 s in 3008.x) with no retry counter, max age or backoff. A job that fails deterministically at start is requeued forever.

Workaround used: stop minion, move cachedir/job_queue aside, truncate log, start.

Expected
  • await_lock should not convert exceptions from the with body into FileLockError (re-raise them unchanged, keep the wrapping for the lock-acquire path only).
  • _handle_decoded_payload's except FileLockError should log the exception (exc_info=True).
  • Queued jobs need a retry limit and/or max age; after that the job is dropped with an error and a return to the master.
Type of salt install

onedir

Major version

3007 (3007.13); defect 1 and 2 still present in 3008.2 / master

What supported OS are you seeing the problem on?

Ubuntu

salt --versions-report output
Salt Version:
          Salt: 3007.13
Python: /opt/saltstack/salt/bin/python3.10 (onedir)
OS: Ubuntu, cPanel hosts

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with salt.utils.files.await_lock and trace its exception handling around the with body, then inspect _handle_decoded_payload and _process_process_queue_async_impl. Confirm that body exceptions remain distinguishable from lock-acquisition failures, that FileLockError logging includes the exception, and that repeatedly failing queued jobs eventually stop requeueing with an error return to the master.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
devops, distributed-systems
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Active
Clarity
Mostly clear
Newbie friendliness
45/100

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