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Reduce lock contention in HttpRemoteTask #13934

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merged 5 commits into from
Sep 2, 2022
Merged

Reduce lock contention in HttpRemoteTask #13934

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f683b7a
Add explicit synchronization section
sopel39 Aug 31, 2022
cbddf8d
Move sentDynamicFiltersVersion out of critical section
sopel39 Aug 31, 2022
0df2757
Move sendPlan out of critical section
sopel39 Aug 31, 2022
61303af
Make outputBuffers fully atomic
sopel39 Aug 31, 2022
00cf20a
Reduce lock contention in HttpRemoteTask
sopel39 Aug 31, 2022
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175 changes: 93 additions & 82 deletions core/trino-main/src/main/java/io/trino/server/remotetask/HttpRemoteTask.java
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Original file line number Diff line number Diff line change
Expand Up @@ -126,13 +126,12 @@ public final class HttpRemoteTask
private final DynamicFiltersFetcher dynamicFiltersFetcher;

private final DynamicFiltersCollector outboundDynamicFiltersCollector;
@GuardedBy("this")
// The version of dynamic filters that has been successfully sent to the worker
private long sentDynamicFiltersVersion = INITIAL_DYNAMIC_FILTERS_VERSION;
private final AtomicLong sentDynamicFiltersVersion = new AtomicLong(INITIAL_DYNAMIC_FILTERS_VERSION);

@GuardedBy("this")
@GuardedBy("httpClient")
private Future<?> currentRequest;
@GuardedBy("this")
@GuardedBy("httpClient")
private long currentRequestStartNanos;
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@GuardedBy("this")
Expand All @@ -146,7 +145,6 @@ public final class HttpRemoteTask
// The keys of this map represent all plan nodes that have "no more splits".
// The boolean value of each entry represents whether the "no more splits" notification is pending delivery to workers.
private final Map<PlanNodeId, Boolean> noMoreSplits = new HashMap<>();
@GuardedBy("this")
private final AtomicReference<OutputBuffers> outputBuffers = new AtomicReference<>();
private final FutureStateChange<Void> whenSplitQueueHasSpace = new FutureStateChange<>();
@GuardedBy("this")
Expand Down Expand Up @@ -415,14 +413,21 @@ public synchronized void noMoreSplits(PlanNodeId sourceId)
}

@Override
public synchronized void setOutputBuffers(OutputBuffers newOutputBuffers)
public void setOutputBuffers(OutputBuffers newOutputBuffers)
{
if (getTaskStatus().getState().isDone()) {
return;
}

if (newOutputBuffers.getVersion() > outputBuffers.get().getVersion()) {
outputBuffers.set(newOutputBuffers);
long previousVersion = outputBuffers.getAndUpdate(previousOutputBuffers -> {
if (newOutputBuffers.getVersion() > previousOutputBuffers.getVersion()) {
return newOutputBuffers;
}

return previousOutputBuffers;
}).getVersion();

if (newOutputBuffers.getVersion() > previousVersion) {
triggerUpdate();
}
}
Expand Down Expand Up @@ -579,73 +584,75 @@ private void triggerUpdate()
}
}

private synchronized void sendUpdate()
private void sendUpdate()
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{
TaskStatus taskStatus = getTaskStatus();
// don't update if the task hasn't been started yet or if it is already finished
if (!started.get() || taskStatus.getState().isDone()) {
return;
}

int currentPendingRequestsCounter = pendingRequestsCounter.get();
if (currentPendingRequestsCounter == 0) {
return;
}
synchronized (httpClient) {
TaskStatus taskStatus = getTaskStatus();
// don't update if the task hasn't been started yet or if it is already finished
if (!started.get() || taskStatus.getState().isDone()) {
return;
}

// if there is a request already running, wait for it to complete
// currentRequest is always cleared when request is complete
if (currentRequest != null) {
return;
}
int currentPendingRequestsCounter = pendingRequestsCounter.get();
if (currentPendingRequestsCounter == 0) {
return;
}

// if throttled due to error, asynchronously wait for timeout and try again
ListenableFuture<Void> errorRateLimit = updateErrorTracker.acquireRequestPermit();
if (!errorRateLimit.isDone()) {
errorRateLimit.addListener(this::sendUpdate, executor);
return;
}
// if there is a request already running, wait for it to complete
// currentRequest is always cleared when request is complete
if (currentRequest != null) {
return;
}

List<SplitAssignment> splitAssignments = getSplitAssignments();
VersionedDynamicFilterDomains dynamicFilterDomains = outboundDynamicFiltersCollector.acknowledgeAndGetNewDomains(sentDynamicFiltersVersion);
// if throttled due to error, asynchronously wait for timeout and try again
ListenableFuture<Void> errorRateLimit = updateErrorTracker.acquireRequestPermit();
if (!errorRateLimit.isDone()) {
errorRateLimit.addListener(this::sendUpdate, executor);
return;
}

// Workers don't need the embedded JSON representation when the fragment is sent
Optional<PlanFragment> fragment = sendPlan.get() ? Optional.of(planFragment.withoutEmbeddedJsonRepresentation()) : Optional.empty();
TaskUpdateRequest updateRequest = new TaskUpdateRequest(
session.toSessionRepresentation(),
session.getIdentity().getExtraCredentials(),
fragment,
splitAssignments,
outputBuffers.get(),
dynamicFilterDomains.getDynamicFilterDomains());
byte[] taskUpdateRequestJson = taskUpdateRequestCodec.toJsonBytes(updateRequest);
if (fragment.isPresent()) {
stats.updateWithPlanBytes(taskUpdateRequestJson.length);
}
if (!dynamicFilterDomains.getDynamicFilterDomains().isEmpty()) {
stats.updateWithDynamicFilterBytes(taskUpdateRequestJson.length);
}
List<SplitAssignment> splitAssignments = getSplitAssignments();
VersionedDynamicFilterDomains dynamicFilterDomains = outboundDynamicFiltersCollector.acknowledgeAndGetNewDomains(sentDynamicFiltersVersion.get());

// Workers don't need the embedded JSON representation when the fragment is sent
Optional<PlanFragment> fragment = sendPlan.get() ? Optional.of(planFragment.withoutEmbeddedJsonRepresentation()) : Optional.empty();
TaskUpdateRequest updateRequest = new TaskUpdateRequest(
session.toSessionRepresentation(),
session.getIdentity().getExtraCredentials(),
fragment,
splitAssignments,
outputBuffers.get(),
dynamicFilterDomains.getDynamicFilterDomains());
byte[] taskUpdateRequestJson = taskUpdateRequestCodec.toJsonBytes(updateRequest);
if (fragment.isPresent()) {
stats.updateWithPlanBytes(taskUpdateRequestJson.length);
}
if (!dynamicFilterDomains.getDynamicFilterDomains().isEmpty()) {
stats.updateWithDynamicFilterBytes(taskUpdateRequestJson.length);
}

HttpUriBuilder uriBuilder = getHttpUriBuilder(taskStatus);
Request request = preparePost()
.setUri(uriBuilder.build())
.setHeader(HttpHeaders.CONTENT_TYPE, MediaType.JSON_UTF_8.toString())
.setBodyGenerator(createStaticBodyGenerator(taskUpdateRequestJson))
.build();
HttpUriBuilder uriBuilder = getHttpUriBuilder(taskStatus);
Request request = preparePost()
.setUri(uriBuilder.build())
.setHeader(HttpHeaders.CONTENT_TYPE, MediaType.JSON_UTF_8.toString())
.setBodyGenerator(createStaticBodyGenerator(taskUpdateRequestJson))
.build();

updateErrorTracker.startRequest();
updateErrorTracker.startRequest();

ListenableFuture<JsonResponse<TaskInfo>> future = httpClient.executeAsync(request, createFullJsonResponseHandler(taskInfoCodec));
currentRequest = future;
currentRequestStartNanos = System.nanoTime();
ListenableFuture<JsonResponse<TaskInfo>> future = httpClient.executeAsync(request, createFullJsonResponseHandler(taskInfoCodec));
currentRequest = future;
currentRequestStartNanos = System.nanoTime();

// if pendingRequestsCounter is still non-zero (e.g. because triggerUpdate was called in the meantime)
// then the request Future callback will send a new update via sendUpdate method call
pendingRequestsCounter.addAndGet(-currentPendingRequestsCounter);
// if pendingRequestsCounter is still non-zero (e.g. because triggerUpdate was called in the meantime)
// then the request Future callback will send a new update via sendUpdate method call
pendingRequestsCounter.addAndGet(-currentPendingRequestsCounter);

Futures.addCallback(
future,
new SimpleHttpResponseHandler<>(new UpdateResponseHandler(splitAssignments, dynamicFilterDomains.getVersion()), request.getUri(), stats),
executor);
Futures.addCallback(
future,
new SimpleHttpResponseHandler<>(new UpdateResponseHandler(splitAssignments, dynamicFilterDomains.getVersion()), request.getUri(), stats),
executor);
}
}

private synchronized List<SplitAssignment> getSplitAssignments()
Expand Down Expand Up @@ -685,26 +692,30 @@ public synchronized void cancel()
}
}

private synchronized void cleanUpTask()
private void cleanUpTask()
{
checkState(getTaskStatus().getState().isDone(), "attempt to clean up a task that is not done yet");

// clear pending splits to free memory
pendingSplits.clear();
pendingSourceSplitCount = 0;
pendingSourceSplitsWeight = 0;
partitionedSplitCountTracker.setPartitionedSplits(PartitionedSplitsInfo.forZeroSplits());
splitQueueHasSpace = true;
whenSplitQueueHasSpace.complete(null, executor);
synchronized (this) {
pendingSplits.clear();
pendingSourceSplitCount = 0;
pendingSourceSplitsWeight = 0;
partitionedSplitCountTracker.setPartitionedSplits(PartitionedSplitsInfo.forZeroSplits());
splitQueueHasSpace = true;
whenSplitQueueHasSpace.complete(null, executor);
}

// clear pending outbound dynamic filters to free memory
outboundDynamicFiltersCollector.acknowledge(Long.MAX_VALUE);

// cancel pending request
if (currentRequest != null) {
currentRequest.cancel(true);
currentRequest = null;
currentRequestStartNanos = 0;
synchronized (httpClient) {
if (currentRequest != null) {
currentRequest.cancel(true);
currentRequest = null;
currentRequestStartNanos = 0;
}
}

taskStatusFetcher.stop();
Expand Down Expand Up @@ -916,15 +927,15 @@ public void success(TaskInfo value)
{
try (SetThreadName ignored = new SetThreadName("UpdateResponseHandler-%s", taskId)) {
try {
sentDynamicFiltersVersion.set(currentRequestDynamicFiltersVersion);
// Remove dynamic filters which were successfully sent to free up memory
outboundDynamicFiltersCollector.acknowledge(currentRequestDynamicFiltersVersion);
sendPlan.set(value.isNeedsPlan());
long currentRequestStartNanos;
synchronized (HttpRemoteTask.this) {
synchronized (httpClient) {
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currentRequest = null;
sendPlan.set(value.isNeedsPlan());
currentRequestStartNanos = HttpRemoteTask.this.currentRequestStartNanos;
sentDynamicFiltersVersion = currentRequestDynamicFiltersVersion;
}
// Remove dynamic filters which were successfully sent to free up memory
outboundDynamicFiltersCollector.acknowledge(currentRequestDynamicFiltersVersion);
updateStats(currentRequestStartNanos);
processTaskUpdate(value, splitAssignments);
updateErrorTracker.requestSucceeded();
Expand All @@ -941,7 +952,7 @@ public void failed(Throwable cause)
try (SetThreadName ignored = new SetThreadName("UpdateResponseHandler-%s", taskId)) {
try {
long currentRequestStartNanos;
synchronized (HttpRemoteTask.this) {
synchronized (httpClient) {
currentRequest = null;
currentRequestStartNanos = HttpRemoteTask.this.currentRequestStartNanos;
}
Expand Down