[GitHub] [kafka] showuon commented on a diff in pull request #13782: Suggest for performance fix: KAFKA-9693 Kafka latency spikes caused by log segment flush on roll - trunk version

["showuon (via GitHub)" <gi...@apache.org>]

showuon commented on code in PR #13782:
URL: https://github.com/apache/kafka/pull/13782#discussion_r1219035983


##########
storage/src/main/java/org/apache/kafka/storage/internals/log/ProducerStateManager.java:
##########
@@ -681,7 +687,12 @@ private static void writeSnapshot(File file, Map<Long, ProducerStateEntry> entri
 
         try (FileChannel fileChannel = FileChannel.open(file.toPath(), StandardOpenOption.CREATE, StandardOpenOption.WRITE)) {
             fileChannel.write(buffer);
-            fileChannel.force(true);
+        }
+
+        if (scheduler != null) {
+            scheduler.scheduleOnce("flush-producer-snapshot", () -> Utils.flushFileQuietly(file.toPath(), "producer-snapshot"));
+        } else {
+            Utils.flushFileQuietly(file.toPath(), "producer-snapshot");

Review Comment:
   After this change, the fileChannel needs to open/close twice under `scheduler == null` case. Maybe we can jsut do it like this:
   ```
   try (FileChannel fileChannel = FileChannel.open(file.toPath(), StandardOpenOption.CREATE, StandardOpenOption.WRITE)) {
               fileChannel.write(buffer);
              if (scheduler == null) {
                   // directly flush to disk
                   fileChannel.force(true);
              }
           }
   
           if (scheduler != null) {
               scheduler.scheduleOnce("flush-producer-snapshot", () -> Utils.flushFileQuietly(file.toPath(), "producer-snapshot"));
           }
   ```
   
   WDYT?



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