ijuma commented on a change in pull request #8467:
URL: https://github.com/apache/kafka/pull/8467#discussion_r413826884
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File path: core/src/main/scala/kafka/log/LogManager.scala
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@@ -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:
`scala.collection.Map` has a `def foreachEntry[U](f: (K, V) => U): Unit`
method that avoids allocating tuples (it's a function with two parameters). If
we want to avoid allocations, we should introduce one such method to `Pool` and
use it here.
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