lbradstreet commented on a change in pull request #8467:
URL: https://github.com/apache/kafka/pull/8467#discussion_r414190233
##########
File path: core/src/main/scala/kafka/log/LogManager.scala
##########
@@ -1003,9 +1003,17 @@ class LogManager(logDirs: Seq[File],
/**
* Map of log dir to logs by topic and partitions in that dir
*/
- private def logsByDir: Map[String, Map[TopicPartition, Log]] = {
- (this.currentLogs.toList ++ this.futureLogs.toList).toMap
- .groupBy { case (_, log) => log.parentDir }
+ def logsByDir: Map[String, Map[TopicPartition, Log]] = {
+ // This code is called often by checkpoint processes and is written in a
way that reduces
+ // allocations and CPU with many topic partitions.
+ // When changing this code please measure the changes with
org.apache.kafka.jmh.server.CheckpointBench
+ val byDir = new mutable.AnyRefMap[String,
mutable.AnyRefMap[TopicPartition, Log]]()
+ def addToDir(tp: TopicPartition, log: Log): Unit = {
+ byDir.getOrElseUpdate(log.parentDir, new
mutable.AnyRefMap[TopicPartition, Log]()).put(tp, log)
+ }
+ currentLogs.foreach { case (tp, log) => addToDir(tp, log) }
+ futureLogs.foreach { case (tp, log) => addToDir(tp, log) }
Review comment:
AFAICT, it easy enough to do something like this:
```
pool.forEach((k,v) => f(k,v))
```
But then we appear to be back to allocating tuples.
It doesn't appear easy to do something like:
```
pool.forEach(kv => f(kv.getKey, kv.getValue))
```
since it's not able to create a BiConsumer for you.
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