ifndef-SleePy commented on a change in pull request #10332:
[FLINK-13905][checkpointing] Separate checkpoint triggering into several
asynchronous stages
URL: https://github.com/apache/flink/pull/10332#discussion_r367778946
##########
File path:
flink-runtime/src/main/java/org/apache/flink/runtime/checkpoint/CheckpointCoordinator.java
##########
@@ -576,85 +648,181 @@ public boolean isShutdown() {
checkpoint.setStatsCallback(callback);
}
- // schedule the timer that will clean up the expired checkpoints
- final Runnable canceller = () -> {
- synchronized (lock) {
- // only do the work if the checkpoint is not
discarded anyways
- // note that checkpoint completion discards the
pending checkpoint object
- if (!checkpoint.isDiscarded()) {
- LOG.info("Checkpoint {} of job {}
expired before completing.", checkpointID, job);
-
- abortPendingCheckpoint(
- checkpoint,
- new
CheckpointException(CheckpointFailureReason.CHECKPOINT_EXPIRED));
- }
- }
- };
+ synchronized (lock) {
- try {
- // re-acquire the coordinator-wide lock
- synchronized (lock) {
- preCheckBeforeTriggeringCheckpoint(isPeriodic,
props.forceCheckpoint());
+ pendingCheckpoints.put(checkpointID, checkpoint);
- LOG.info("Triggering checkpoint {} @ {} for job
{}.", checkpointID, timestamp, job);
+ ScheduledFuture<?> cancellerHandle = timer.schedule(
+ new CheckpointCanceller(checkpoint),
+ checkpointTimeout, TimeUnit.MILLISECONDS);
- pendingCheckpoints.put(checkpointID,
checkpoint);
+ if (!checkpoint.setCancellerHandle(cancellerHandle)) {
+ // checkpoint is already disposed!
+ cancellerHandle.cancel(false);
+ }
+ }
- ScheduledFuture<?> cancellerHandle =
timer.schedule(
- canceller,
- checkpointTimeout,
TimeUnit.MILLISECONDS);
+ LOG.info("Triggering checkpoint {} @ {} for job {}.",
checkpointID, timestamp, job);
+ return checkpoint;
+ }
- if
(!checkpoint.setCancellerHandle(cancellerHandle)) {
- // checkpoint is already disposed!
- cancellerHandle.cancel(false);
- }
+ /**
+ * Snapshot master hook states asynchronously.
+ *
+ * @param checkpoint the pending checkpoint
+ * @return the future represents master hook states are finished or not
+ */
+ private CompletableFuture<Void> snapshotMasterState(PendingCheckpoint
checkpoint) {
+ if (masterHooks.isEmpty()) {
+ return CompletableFuture.completedFuture(null);
+ }
- // TODO, asynchronously snapshots master hook
without waiting here
- for (MasterTriggerRestoreHook<?> masterHook :
masterHooks.values()) {
- final MasterState masterState =
-
MasterHooks.triggerHook(masterHook, checkpointID, timestamp, executor)
- .get(checkpointTimeout,
TimeUnit.MILLISECONDS);
-
checkpoint.acknowledgeMasterState(masterHook.getIdentifier(), masterState);
- }
-
Preconditions.checkState(checkpoint.areMasterStatesFullyAcknowledged());
- }
- // end of lock scope
+ final long checkpointID = checkpoint.getCheckpointId();
+ final long timestamp = checkpoint.getCheckpointTimestamp();
- final CheckpointOptions checkpointOptions = new
CheckpointOptions(
- props.getCheckpointType(),
-
checkpointStorageLocation.getLocationReference());
+ final CompletableFuture<Void> masterStateCompletableFuture =
new CompletableFuture<>();
+ for (MasterTriggerRestoreHook<?> masterHook :
masterHooks.values()) {
+ MasterHooks
+ .triggerHook(masterHook, checkpointID,
timestamp, executor)
+ .whenCompleteAsync((masterState, throwable) -> {
+ try {
+ synchronized (lock) {
+ if
(masterStateCompletableFuture.isDone()) {
+ return;
+ }
+ if
(checkpoint.isDiscarded()) {
+ throw new
IllegalStateException(
+
"Checkpoint " + checkpointID + " has been discarded");
+ }
+ if (throwable == null) {
+
checkpoint.acknowledgeMasterState(
+
masterHook.getIdentifier(), masterState);
+ if
(checkpoint.areMasterStatesFullyAcknowledged()) {
+
masterStateCompletableFuture.complete(null);
+ }
+ } else {
+
masterStateCompletableFuture.completeExceptionally(throwable);
+ }
+ }
+ } catch (Throwable t) {
+
masterStateCompletableFuture.completeExceptionally(t);
+ }
+ }, timer);
+ }
+ return masterStateCompletableFuture;
+ }
- // send the messages to the tasks that trigger their
checkpoint
- for (Execution execution: executions) {
- if (props.isSynchronous()) {
-
execution.triggerSynchronousSavepoint(checkpointID, timestamp,
checkpointOptions, advanceToEndOfTime);
- } else {
-
execution.triggerCheckpoint(checkpointID, timestamp, checkpointOptions);
- }
+ /**
+ * Snapshot task state.
+ *
+ * @param timestamp the timestamp of this checkpoint reques
+ * @param checkpointID the checkpoint id
+ * @param checkpointStorageLocation the checkpoint location
+ * @param props the checkpoint properties
+ * @param executions the executions which should be triggered
+ * @param advanceToEndOfTime Flag indicating if the source should
inject a {@code MAX_WATERMARK}
+ * in the pipeline to fire any registered
event-time timers.
+ */
+ private void snapshotTaskState(
+ long timestamp,
+ long checkpointID,
+ CheckpointStorageLocation checkpointStorageLocation,
+ CheckpointProperties props,
+ Execution[] executions,
+ boolean advanceToEndOfTime) {
+
+ final CheckpointOptions checkpointOptions = new
CheckpointOptions(
+ props.getCheckpointType(),
+ checkpointStorageLocation.getLocationReference());
+
+ // send the messages to the tasks that trigger their checkpoint
+ for (Execution execution: executions) {
+ if (props.isSynchronous()) {
+
execution.triggerSynchronousSavepoint(checkpointID, timestamp,
checkpointOptions, advanceToEndOfTime);
+ } else {
+ execution.triggerCheckpoint(checkpointID,
timestamp, checkpointOptions);
}
-
- numUnsuccessfulCheckpointsTriggers.set(0);
- return checkpoint.getCompletionFuture();
}
- catch (Throwable t) {
- int numUnsuccessful =
numUnsuccessfulCheckpointsTriggers.incrementAndGet();
- LOG.warn("Failed to trigger checkpoint {} for job {}.
({} consecutive failed attempts so far)",
- checkpointID, job, numUnsuccessful, t);
+ }
- synchronized (lock) {
- if (!checkpoint.isDiscarded()) {
- abortPendingCheckpoint(
- checkpoint,
- new CheckpointException(
-
CheckpointFailureReason.TRIGGER_CHECKPOINT_FAILURE, t));
+ /**
+ * Trigger request is successful.
+ * NOTE, it must be invoked if trigger request is successful.
+ */
+ private void onTriggerSuccess() {
+ isTriggering = false;
+ numUnsuccessfulCheckpointsTriggers.set(0);
+ checkQueuedCheckpointTriggerRequest();
+ }
+
+ /**
+ * The trigger request is failed prematurely without a proper
initialization.
+ * There is no resource to release, but the completion promise needs to
fail manually here.
+ *
+ * @param onCompletionPromise the completion promise of the
checkpoint/savepoint
+ * @param throwable the reason of trigger failure
+ */
+ private void onTriggerFailure(
+ CompletableFuture<CompletedCheckpoint> onCompletionPromise,
Throwable throwable) {
+ final CheckpointException checkpointException =
+
getCheckpointException(CheckpointFailureReason.TRIGGER_CHECKPOINT_FAILURE,
throwable);
+ onCompletionPromise.completeExceptionally(checkpointException);
+ onTriggerFailure((PendingCheckpoint) null, checkpointException);
+ }
+
+ /**
+ * The trigger request is failed.
+ * NOTE, it must be invoked if trigger request is failed.
+ *
+ * @param checkpoint the pending checkpoint which is failed. It could
be null if it's failed
+ * prematurely without a proper initialization.
+ * @param throwable the reason of trigger failure
+ */
+ private void onTriggerFailure(@Nullable PendingCheckpoint checkpoint,
Throwable throwable) {
+ try {
Review comment:
Yes, you are right, we need some checking here. As mentioned above, it's not
easy (or a bit hacky) to check current thread for a `ScheduledExecutor`. Since
the timer thread would be abandoned when we put all these codes into main
thread, I think we should not spending too much time on this. We could do that
in main thread.
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