Reduce allocations in VersionedEventStore#retentionEvents #7118
+43
−40
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
Generate changelog in
|
jeremyk-91
reviewed
Jun 6, 2024
| .limit(numToRetention) | ||
| .forEachOrdered(entry -> { | ||
| .map(entry -> { | ||
| eventMap.remove(entry.getKey()); |
There was a problem hiding this comment.
It looks like the original implementation also did this, but this arrangement of removing from the map seems worrying in terms of non-interference, especially since the entrySet() contract suggests that we shouldn't edit the map?
There was a problem hiding this comment.
We can revert this portion if desired.
eventMap is a ConcurrentSkipListMap whose entrySet() iterator/stream
is weakly consistent. We can safely remove as we traverse the events to retention.
There was a problem hiding this comment.
I'd prefer to keep this as a stream as it avoid some of the Object[] allocations due to intermediate List and the semantics are the same
jeremyk-91
approved these changes
Jun 24, 2024
|
Failed to push a commit onto develop to move @unreleased changelogs |
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Outdated suggestions cannot be applied.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.
General
Before this PR:
AtlasDB clients showing significant allocations of
Object[]when constructingnew ArrayList<>(numToRetention)inVersionedEventStore#retentionEventsatlasdb/atlasdb-impl-shared/src/main/java/com/palantir/atlasdb/keyvalue/api/watch/VersionedEventStore.java
Lines 77 to 86 in 68ebc00
After this PR:
==COMMIT_MSG==
Reduce allocations in VersionedEventStore#retentionEvents
==COMMIT_MSG==
Priority:
Concerns / possible downsides (what feedback would you like?):
Is documentation needed?:
Compatibility
Does this PR create any API breaks (e.g. at the Java or HTTP layers) - if so, do we have compatibility?:
Does this PR change the persisted format of any data - if so, do we have forward and backward compatibility?:
The code in this PR may be part of a blue-green deploy. Can upgrades from previous versions safely coexist? (Consider restarts of blue or green nodes.):
Does this PR rely on statements being true about other products at a deployment - if so, do we have correct product dependencies on these products (or other ways of verifying that these statements are true)?:
Does this PR need a schema migration?
Testing and Correctness
What, if any, assumptions are made about the current state of the world? If they change over time, how will we find out?:
What was existing testing like? What have you done to improve it?:
If this PR contains complex concurrent or asynchronous code, is it correct? The onus is on the PR writer to demonstrate this.:
If this PR involves acquiring locks or other shared resources, how do we ensure that these are always released?:
Execution
How would I tell this PR works in production? (Metrics, logs, etc.):
Has the safety of all log arguments been decided correctly?:
Will this change significantly affect our spending on metrics or logs?:
How would I tell that this PR does not work in production? (monitors, etc.):
If this PR does not work as expected, how do I fix that state? Would rollback be straightforward?:
If the above plan is more complex than “recall and rollback”, please tag the support PoC here (if it is the end of the week, tag both the current and next PoC):
Scale
Would this PR be expected to pose a risk at scale? Think of the shopping product at our largest stack.:
Would this PR be expected to perform a large number of database calls, and/or expensive database calls (e.g., row range scans, concurrent CAS)?:
Would this PR ever, with time and scale, become the wrong thing to do - and if so, how would we know that we need to do something differently?:
Development Process
Where should we start reviewing?:
If this PR is in excess of 500 lines excluding versions lock-files, why does it not make sense to split it?:
Please tag any other people who should be aware of this PR:
@jeremyk-91
@sverma30
@raiju