vere: use fcntl advisory locks on pidfile#697
Merged
Merged
Conversation
pkova
approved these changes
Aug 6, 2024
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The PR replaces vere's current (buggy, insufficient) lockfile mechanism with an advisory
fcntl()write lock (F_SETLK,F_WRLCK) on the first byte of vere's PID file ($pier/.vere.lock). It does not (yet?) include the functionality to kill the lock-holder and take over the pier, as I'm not sure that's desirable.There have been many problems with vere's current lockfile implementation. The biggest advantage of this approach is that the lock is automatically released if the process is killed or the host system crashes. The biggest question is: does it work reliably across docker shared volumes, virtual machines, &c.