ocadaruma commented on code in PR #15993:
URL: https://github.com/apache/kafka/pull/15993#discussion_r1625200232
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storage/src/main/java/org/apache/kafka/storage/internals/epoch/LeaderEpochFileCache.java:
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@@ -305,22 +341,23 @@ public Map.Entry<Integer, Long> endOffsetFor(int
requestedEpoch, long logEndOffs
/**
* Removes all epoch entries from the store with start offsets greater
than or equal to the passed offset.
+ * <p>
+ * Checkpoint-flushing is done asynchronously.
*/
public void truncateFromEnd(long endOffset) {
lock.writeLock().lock();
try {
- Optional<EpochEntry> epochEntry = latestEntry();
- if (endOffset >= 0 && epochEntry.isPresent() &&
epochEntry.get().startOffset >= endOffset) {
- List<EpochEntry> removedEntries = removeFromEnd(x ->
x.startOffset >= endOffset);
-
- // We intentionally don't force flushing change to the device
here because:
+ List<EpochEntry> removedEntries = truncateFromEnd(epochs,
endOffset);
+ if (!removedEntries.isEmpty()) {
+ // We flush the change to the device in the background because:
// - To avoid fsync latency
// * fsync latency could be huge on a disk glitch, which is
not rare in spinning drives
// * This method is called by ReplicaFetcher threads, which
could block replica fetching
// then causing ISR shrink or high produce response time
degradation in remote scope on high fsync latency.
- // - Even when stale epochs remained in LeaderEpoch file due
to the unclean shutdown, it will be handled by
- // another truncateFromEnd call on log loading procedure so
it won't be a problem
- writeToFile(false);
+ // - We still flush the change in #assign synchronously,
meaning that it's guaranteed that the checkpoint file always has no missing
entries.
+ // * Even when stale epochs are restored from the checkpoint
file after the unclean shutdown, it will be handled by
+ // another truncateFromEnd call on log loading procedure,
so it won't be a problem
+ scheduler.scheduleOnce("leader-epoch-cache-flush-" +
topicPartition, this::writeToFileForTruncation);
Review Comment:
Not strictly necessary. I just followed some of existing scheduled tasks's
convention (e.g.
https://github.com/apache/kafka/blob/c24f94936d4370b2a3f3bfad42c56198208079b4/core/src/main/scala/kafka/coordinator/transaction/TransactionStateManager.scala#L571)
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