Default to single thread for server list updates #514
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
| int corePoolSize = getCorePoolSize(); | ||
| defaultServerListUpdateExecutor.setCorePoolSize(corePoolSize); | ||
| defaultServerListUpdateExecutor.setMaximumPoolSize(corePoolSize * 5); | ||
| defaultServerListUpdateExecutor.setCorePoolSize(getCorePoolSize()); |
There was a problem hiding this comment.
FYI, in JDK9, they added more error checking when you call setCorePoolSize, so if you attempt to resize higher than the maximum pool size, it'll error out. We found this within Hystrix as well : Netflix/Hystrix#1874 (comment)
Generally, you can just flip them, but then the inverse is true if you try to resize the max lower. Not sure if we need to accommodate that, but something to be aware of.
nicholashagen
approved these changes
Jul 17, 2023
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Outdated suggestions cannot be applied.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.
Multi-threading on the server list refresher makes assumptions about the lb state management that may not necessarily be true. Especially for LB extensions, these assumptions aren't enforceable through the interfaces provided.
Generally a single thread on the JVM dedicated for pushing these updates should work for most cases, and mitigates concurrency issues seen recently, on some apps.
The props exist for individual apps to override this, when necessary.
In terms of validation, this change was validated in our Zuul deployment through long running canaries that didn't show any regression.