Add gc monitor to warn users about excessive gc #5812
Merged
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
It is not uncommon in large projects for the jvm to silently be running frequent full gcs in the background. This can slow progress to a crawl. Usually the fix is to bump the -Xmx parameter but if the users do not realize that their tasks are slow because of gc thrashing, they may not think to do that. This PR adds a monitor that hooks into the jvm's event notification system to keep track of how much time is spent in GC. If the ratio of the amount of time in gc to the total elapsed time exceeds some threshold, we emit a warning. I was motivated to do this because publishLocal can take forever in the zinc project because a 1G heap isn't big enough.
|
Here it is in action in the zinc project: |
eed3si9n
approved these changes
Sep 6, 2020
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Outdated suggestions cannot be applied.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.
Suggestion cannot be applied right now. Please check back later.
Fixes #5044
It is not uncommon in large projects for the jvm to silently be running
frequent full gcs in the background. This can slow progress to a crawl.
Usually the fix is to bump the -Xmx parameter but if the users do not
realize that their tasks are slow because of gc thrashing, they may not
think to do that. This PR adds a monitor that hooks into the jvm's event
notification system to keep track of how much time is spent in GC. If
the ratio of the amount of time in gc to the total elapsed time exceeds
some threshold, we emit a warning.
I was motivated to do this because publishLocal can take forever in the
zinc project because a 1G heap isn't big enough.