mridulm commented on code in PR #2462:
URL: https://github.com/apache/celeborn/pull/2462#discussion_r1568117997
##########
client/src/main/scala/org/apache/celeborn/client/ChangePartitionManager.scala:
##########
@@ -79,14 +81,17 @@ class ChangePartitionManager(
batchHandleChangePartitionExecutors.submit {
new Runnable {
override def run(): Unit = {
- val distinctPartitions = requests.synchronized {
- // For each partition only need handle one request
- requests.asScala.filter { case (partitionId, _) =>
-
!inBatchPartitions.get(shuffleId).contains(partitionId)
- }.map { case (partitionId, request) =>
- inBatchPartitions.get(shuffleId).add(partitionId)
- request.asScala.toArray.maxBy(_.epoch)
- }.toArray
+ val distinctPartitions = {
+ requests.asScala.map { case (partitionId, request) =>
+ locks(partitionId % locks.length).synchronized {
+ if (!inBatchPartitions.contains(partitionId)) {
+ inBatchPartitions.get(shuffleId).add(partitionId)
+ Some(request.asScala.toArray.maxBy(_.epoch))
+ } else {
+ None
+ }
+ }
+ }.filter(_.isDefined).map(_.get).toArray
Review Comment:
I am not so sure of this change - it feels like it will have a lot more
contention - as each entry in the `requests` map will need to acquire a lock -
while uncontented locks are cheap to acquire, it is not zero cost still.
If you have a test bed to validate perf, how about this ?
```
val batchPartitions = inBatchPartitions.get(shuffleId)
val distinctPartitions = requests.synchronized {
// For each partition only need handle one request
requests.asScala.filter { case (partitionId, _) =>
!batchPartitions.contains(partitionId)
}.map { case (partitionId, request) =>
batchPartitions.add(partitionId)
request.asScala.maxBy(_.epoch)
}.toArray
}
```
Essentially minimize the time within the synchronized block itself by
removing unnecessary costs.
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
