dnsdist: Fix a hang when removing a server with more than one socket #9900
Conversation
This file contains 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
There was a lock starvation issue when removing a server with more than one socket in use (`sockets` greater than 1 on the corresponding `newServer` directive), because the mutex protecting the sockets array would never be released long enough by the responder thread to allow the thread stopping the server to acquire it. This commit fixes that by marking the server as stopped right away, before acquiring the lock, and also making sure that the responder thread is woken up regularly (every second, even without any query to process) and that it checks whether the server has been stopped just after that. The issue was introduced in be55a20, and backported to 1.5.1 in f0d4831.
8 tasks
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
Short description
There was a lock starvation issue when removing a server with more than one socket in use (
socketsgreater than 1 on the correspondingnewServerdirective), because the mutex protecting the sockets array would never be released long enough by the responder thread to allow the thread stopping the server to acquire it.This commit fixes that by marking the server as stopped right away, before acquiring the lock, and also making sure that the responder thread is woken up regularly (every second, even without any query to process) and that it checks whether the server has been stopped just after that.
The issue was introduced in be55a20, and backported to 1.5.1 in f0d4831.
Checklist
I have: