dnsdist: Prevent race while creating new TCP worker threads #4764
Conversation
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
We try very hard to avoid using locks, but we need to prevent two threads inserting into the TCP workers vector concurrently. While this can't happen at runtime since the healthcheck thread is the only one calling `g_tcpclientthreads->addTCPClientThread()`, this might happen at startup time because we start the TCP acceptor threads one after another and they all call it once. This might result, for example, in one vector entry being overwritten and another one remaining value-initialized to zero.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
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Outdated suggestions cannot be applied.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.
Short description
We try very hard to avoid using locks, but we need to prevent two threads inserting into the TCP workers vector concurrently. While this can't happen at runtime since the healthcheck thread is the only one calling
g_tcpclientthreads->addTCPClientThread(), this might happen at startup time because we start the TCP acceptor threads one after another and they all call it once. This might result, for example, in one vector entry being overwritten and another one remaining value-initialized to zero.Reported and very kindly investigated by @paddg (thanks!).
Checklist
I have: