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Merged
kingherc merged 4 commits into from
Sep 15, 2025
Merged

flushOnIdle use tryWithEngineOrNull #134157

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3570258
flushOnIdle use tryWithEngineOrNull
kingherc Sep 4, 2025
6bd9a91
Try with engine also inside flush thread
kingherc Sep 5, 2025
c0ad890
Merge remote-tracking branch 'origin/main' into non-issue/flush-idle-…
kingherc Sep 5, 2025
4e079c8
Modify assertion a bit
kingherc Sep 5, 2025
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67 changes: 43 additions & 24 deletions server/src/main/java/org/elasticsearch/index/shard/IndexShard.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1528,6 +1528,10 @@ public Engine.FlushResult flush(FlushRequest request) {
* @param listener to notify after full durability has been achieved
*/
public void flush(FlushRequest request, ActionListener<Engine.FlushResult> listener) {
flush(request, this::getEngine, listener);
}

protected void flush(FlushRequest request, Supplier<Engine> engine, ActionListener<Engine.FlushResult> listener) {
final boolean waitIfOngoing = request.waitIfOngoing();
final boolean force = request.force();
logger.trace("flush with {}", request);
Expand All @@ -1539,7 +1543,9 @@ public void flush(FlushRequest request, ActionListener<Engine.FlushResult> liste
*/
verifyNotClosed();
final long startTime = System.nanoTime();
getEngine().flush(force, waitIfOngoing, ActionListener.runBefore(l, () -> flushMetric.inc(System.nanoTime() - startTime)));
assert engine != null : "engine supplier is null";
assert engine.get() != null : "engine is null";
engine.get().flush(force, waitIfOngoing, ActionListener.runBefore(l, () -> flushMetric.inc(System.nanoTime() - startTime)));
});
}

Expand Down Expand Up @@ -2545,33 +2551,46 @@ public void addShardFailureCallback(Consumer<ShardFailure> onShardFailure) {
* indexing operation, so we can flush the index.
*/
public void flushOnIdle(long inactiveTimeNS) {
Engine engineOrNull = getEngineOrNull();
if (engineOrNull != null && System.nanoTime() - engineOrNull.getLastWriteNanos() >= inactiveTimeNS) {
boolean wasActive = active.getAndSet(false);
if (wasActive) {
logger.debug("flushing shard on inactive");
threadPool.executor(ThreadPool.Names.FLUSH)
.execute(() -> flush(new FlushRequest().waitIfOngoing(false).force(false), new ActionListener<>() {
@Override
public void onResponse(Engine.FlushResult flushResult) {
if (flushResult.skippedDueToCollision()) {
// In case an ongoing flush was detected, revert active flag so that a next flushOnIdle request
// will retry (#87888)
tryWithEngineOrNull(engineOrNull -> {
if (engineOrNull != null && System.nanoTime() - engineOrNull.getLastWriteNanos() >= inactiveTimeNS) {
boolean wasActive = active.getAndSet(false);
if (wasActive) {
logger.debug("flushing shard on inactive");
threadPool.executor(ThreadPool.Names.FLUSH).execute(() -> {
tryWithEngineOrNull(engine -> {
if (engine == null) {
// Revert active flag so that a next flushOnIdle request will retry
active.set(true);
}
periodicFlushMetric.inc();
}
} else {
flush(new FlushRequest().waitIfOngoing(false).force(false), () -> engine, new ActionListener<>() {
@Override
public void onResponse(Engine.FlushResult flushResult) {
if (flushResult.skippedDueToCollision()) {
// In case an ongoing flush was detected, revert active flag so that a next flushOnIdle request
// will retry (#87888)
active.set(true);
}
periodicFlushMetric.inc();
}

@Override
public void onFailure(Exception e) {
if (state != IndexShardState.CLOSED) {
active.set(true);
logger.warn("failed to flush shard on inactive", e);
@Override
public void onFailure(Exception e) {
if (state != IndexShardState.CLOSED) {
active.set(true);
logger.warn("failed to flush shard on inactive", e);
}
}
});
}
}
}));
return null;
});
});
}
} else {
logger.trace(() -> "flush on idle skipped as it is either closed, engine being reset, or has been recently written to");
}
}
return null;
});
}

public boolean isActive() {
Expand Down
60 changes: 60 additions & 0 deletions server/src/test/java/org/elasticsearch/index/shard/IndexShardTests.java
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Original file line number Diff line number Diff line change
Expand Up @@ -4497,6 +4497,66 @@ public Engine.Delete preDelete(ShardId shardId, Engine.Delete delete) {
closeShards(shard);
}

@TestLogging(reason = "testing traces of concurrent flush and engine reset", value = "org.elasticsearch.index.shard.IndexShard:TRACE")
public void testFlushOnIdleDoesNotWaitWhileEngineIsReset() throws Exception {
final var preparedForReset = new AtomicBoolean();
final var shard = newStartedShard(true, Settings.EMPTY, config -> {
if (preparedForReset.get()) {
return new ReadOnlyEngine(config, null, new TranslogStats(), false, Function.identity(), true, true);
} else {
return new InternalEngine(config) {
@Override
public void prepareForEngineReset() throws IOException {
assertTrue(preparedForReset.compareAndSet(false, true));
}
};
}
});
final var engineResetLock = shard.getEngine().getEngineConfig().getEngineResetLock();

final var release = new CountDownLatch(1);
final var reset = new PlainActionFuture<Void>();
final var resetEngineThread = new Thread(() -> {
try {
shard.acquirePrimaryOperationPermit(reset.delegateFailure((l, permit) -> {
try (permit) {
shard.resetEngine(newEngine -> {
assertThat(engineResetLock.isWriteLockedByCurrentThread(), equalTo(true));
assertThat(newEngine, instanceOf(ReadOnlyEngine.class));
safeAwait(release);
});
assertThat(preparedForReset.get(), equalTo(true));
l.onResponse(null);
}
}), EsExecutors.DIRECT_EXECUTOR_SERVICE);
} catch (Exception e) {
reset.onFailure(e);
}
});
resetEngineThread.start();

assertBusy(() -> assertThat(engineResetLock.isWriteLocked(), equalTo(true)));

try (var mockLog = MockLog.capture(IndexShard.class)) {
mockLog.addExpectation(
new MockLog.SeenEventExpectation(
"should see flush on idle returning since it will not wait for the engine reset",
IndexShard.class.getCanonicalName(),
Level.TRACE,
"flush on idle skipped"
)
);
shard.flushOnIdle(0);
mockLog.awaitAllExpectationsMatched();
}

release.countDown();
safeGet(reset);
assertThat(engineResetLock.isWriteLocked(), equalTo(false));
resetEngineThread.join();
closeShards(shard);
}

public void testMultiplePeriodicFlushesCanBeTriggeredBeforeTheyAreDurable() throws Exception {
List<ActionListener<Engine.FlushResult>> pendingListeners = Collections.synchronizedList(new ArrayList<>());
// Ensure that a single document forces a flush after each write
Expand Down