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_r366676607
##########
File path:
flink-runtime/src/main/java/org/apache/flink/runtime/checkpoint/CheckpointCoordinator.java
##########
@@ -484,77 +484,158 @@ public boolean isShutdown() {
CheckpointProperties props,
@Nullable String externalSavepointLocation,
boolean isPeriodic,
- boolean advanceToEndOfTime) throws CheckpointException {
+ boolean advanceToEndOfTime) {
if (advanceToEndOfTime && !(props.isSynchronous() &&
props.isSavepoint())) {
- throw new IllegalArgumentException("Only synchronous
savepoints are allowed to advance the watermark to MAX.");
+ return FutureUtils.completedExceptionally(new
IllegalArgumentException(
+ "Only synchronous savepoints are allowed to
advance the watermark to MAX."));
}
- // make some eager pre-checks
+ final CompletableFuture<CompletedCheckpoint>
onCompletionPromise =
+ new CompletableFuture<>();
synchronized (lock) {
- preCheckBeforeTriggeringCheckpoint(isPeriodic,
props.forceCheckpoint());
- }
-
- // check if all tasks that we need to trigger are running.
- // if not, abort the checkpoint
- Execution[] executions = new Execution[tasksToTrigger.length];
- for (int i = 0; i < tasksToTrigger.length; i++) {
- Execution ee =
tasksToTrigger[i].getCurrentExecutionAttempt();
- if (ee == null) {
- LOG.info("Checkpoint triggering task {} of job
{} is not being executed at the moment. Aborting checkpoint.",
-
tasksToTrigger[i].getTaskNameWithSubtaskIndex(),
- job);
- throw new
CheckpointException(CheckpointFailureReason.NOT_ALL_REQUIRED_TASKS_RUNNING);
- } else if (ee.getState() == ExecutionState.RUNNING) {
- executions[i] = ee;
- } else {
- LOG.info("Checkpoint triggering task {} of job
{} is not in state {} but {} instead. Aborting checkpoint.",
-
tasksToTrigger[i].getTaskNameWithSubtaskIndex(),
- job,
- ExecutionState.RUNNING,
- ee.getState());
- throw new
CheckpointException(CheckpointFailureReason.NOT_ALL_REQUIRED_TASKS_RUNNING);
+ if (isTriggering || !triggerRequestQueue.isEmpty()) {
+ // we can't trigger checkpoint directly if
there is a trigger request being processed
+ // or queued
+ triggerRequestQueue.add(new
CheckpointTriggerRequest(
+ timestamp,
+ props,
+ externalSavepointLocation,
+ isPeriodic,
+ advanceToEndOfTime,
+ onCompletionPromise));
+ return onCompletionPromise;
}
}
+ startTriggeringCheckpoint(
+ timestamp,
+ props,
+ externalSavepointLocation,
+ isPeriodic,
+ advanceToEndOfTime,
+ onCompletionPromise);
+ return onCompletionPromise;
+ }
- // next, check if all tasks that need to acknowledge the
checkpoint are running.
- // if not, abort the checkpoint
- Map<ExecutionAttemptID, ExecutionVertex> ackTasks = new
HashMap<>(tasksToWaitFor.length);
+ private void startTriggeringCheckpoint(
+ long timestamp,
+ CheckpointProperties props,
+ @Nullable String externalSavepointLocation,
+ boolean isPeriodic,
+ boolean advanceToEndOfTime,
+ CompletableFuture<CompletedCheckpoint> onCompletionPromise) {
- for (ExecutionVertex ev : tasksToWaitFor) {
- Execution ee = ev.getCurrentExecutionAttempt();
- if (ee != null) {
- ackTasks.put(ee.getAttemptId(), ev);
- } else {
- LOG.info("Checkpoint acknowledging task {} of
job {} is not being executed at the moment. Aborting checkpoint.",
-
ev.getTaskNameWithSubtaskIndex(),
- job);
- throw new
CheckpointException(CheckpointFailureReason.NOT_ALL_REQUIRED_TASKS_RUNNING);
+ try {
+ // make some eager pre-checks
+ synchronized (lock) {
+ preCheckBeforeTriggeringCheckpoint(isPeriodic,
props.forceCheckpoint());
}
- }
- // we will actually trigger this checkpoint!
+ final Execution[] executions = getTriggerExecutions();
+ final Map<ExecutionAttemptID, ExecutionVertex> ackTasks
= getAckTasks();
+
+ // we will actually trigger this checkpoint!
+ Preconditions.checkState(!isTriggering);
+ isTriggering = true;
+
+ // keep a reference outside the async calls
+ final AtomicReference<PendingCheckpoint>
currentCheckpointRef = new AtomicReference<>();
+ initializeCheckpoint(props, externalSavepointLocation)
+
.thenComposeAsync((checkpointIdAndStorageLocation) -> {
+ synchronized (lock) {
+ // since we haven't created the
PendingCheckpoint yet, we need to check the
+ // global state here.
+ // otherwise the
PendingCheckpoint would be discarded if the global state
+ // changed (shutdown or
periodic scheduling stopped)
+ if (shutdown) {
+ throw new
CompletionException(new
CheckpointException(CheckpointFailureReason.CHECKPOINT_COORDINATOR_SHUTDOWN));
+ }
+ if (isPeriodic &&
!periodicScheduling) {
+ throw new
CompletionException(new
CheckpointException(CheckpointFailureReason.PERIODIC_SCHEDULER_SHUTDOWN));
+ }
+ }
+ final PendingCheckpoint
pendingCheckpoint = createPendingCheckpoint(
+ timestamp,
+ props,
+ ackTasks,
+ isPeriodic,
+
checkpointIdAndStorageLocation.checkpointId,
+
checkpointIdAndStorageLocation.checkpointStorageLocation,
+ onCompletionPromise);
+
currentCheckpointRef.set(pendingCheckpoint);
+
+ LOG.info("Triggering checkpoint {} @ {}
for job {}.",
+
checkpointIdAndStorageLocation.checkpointId, timestamp, job);
+ return
snapshotMasterState(pendingCheckpoint);
+ }, timer)
+ .thenRun(() -> {
+ // it must be executed in timer thread.
+ // we could add a checking after
replace timer with main thread
+ final PendingCheckpoint checkpoint =
currentCheckpointRef.get();
+ checkState(!checkpoint.isDiscarded());
+ snapshotTaskState(
+ timestamp,
+ checkpoint.getCheckpointId(),
+
checkpoint.getCheckpointStorageLocation(),
+ props,
+ executions,
+ advanceToEndOfTime);
+ onTriggerSuccess();
+ })
+ .whenCompleteAsync((ignored, throwable) -> {
+ // the error handling has to be
executed in timer thread
+ if (throwable != null) {
+ // the initialization might not
be finished yet
+ if (currentCheckpointRef.get()
== null) {
+
onTriggerFailure(onCompletionPromise, throwable);
+ } else {
+
onTriggerFailure(currentCheckpointRef.get(), throwable);
+ }
+ }
+ }, timer);
Review comment:
BTW, I replaced the `checkState(!checkpoint.isDiscarded());` by
`!checkpoint.isDiscarded()`. Because I found there is a possibility that
`PendingCheckpoint` might be cancelled during the asynchronous call if there is
no master hook (otherwise `snapshotMasterState` would check state of
`PendingCheckpoint`).
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