[dlog] use Atomic***FieldUpdater and LongAdder if possible #1299
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
Atomic**FieldUpdater + volatile provides similar guarantees as Atomic*** but use much fewer memory. In dlog, when handling large number of streams, there can be a lot of Atomic*** fields with `LogHandler`, `SegmentWriter` and such. Switching using Atomic*** to using Atomic**FieldUpdater + volatile will save a lot of memory. See [details](http://normanmaurer.me/blog/2013/10/28/Lesser-known-concurrent-classes-Part-1/) LongAdder is less contended across threads, which is more preferable to AtomicLong when multiple threads update a common sum. E.g. SampledMovingAverageRate. Switching to use LongAdder if AtomicLong is not needed. See [details](https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/atomic/LongAdder.html)
|
/cc @philipsu522 for reviews |
eolivelli
approved these changes
Mar 28, 2018
|
LGTM! |
|
@jiazhai - Change to AtomicFieldUpdater only help a lot when you have a lot of these |
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Outdated suggestions cannot be applied.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.
Descriptions of the changes in this PR:
AtomicFieldUpdater + volatile provides similar guarantees as Atomic but use much fewer memory.
In dlog, when handling large number of streams, there can be a lot of Atomic fields with
LogHandler,SegmentWriterand such.Switching using Atomic to using AtomicFieldUpdater + volatile will save a lot of memory. See details
LongAdder is less contended across threads, which is more preferable to AtomicLong when multiple threads update a common sum. E.g. SampledMovingAverageRate.
Switching to use LongAdder if AtomicLong is not needed. See details
Master Issue: #