private void dropSubsumedCheckpoints(long timestamp) {
Iterator<Map.Entry<Long, PendingCheckpoint>> entries = pendingCheckpoints.entrySet().iterator();
while (entries.hasNext()) {
PendingCheckpoint p = entries.next().getValue();
if (p.getCheckpointTimestamp() < timestamp) {
rememberRecentCheckpointId(p.getCheckpointId());
p.discard(userClassLoader);
onCancelCheckpoint(p.getCheckpointId());
entries.remove();
}
}
}
/**
* Shuts down the checkpoint coordinator.
*
* <p>After this method has been called, the coordinator does not accept and further messages and
* cannot trigger any further checkpoints.
*/
public void shutdown() throws Exception {
synchronized (lock) {
try {
if (!shutdown) {
shutdown = true;
LOG.info("Stopping checkpoint coordinator for job " + job);
periodicScheduling = false;
triggerRequestQueued = false;
// shut down the thread that handles the timeouts and pending triggers
timer.cancel();
// make sure that the actor does not linger
if (jobStatusListener != null) {
jobStatusListener.tell(PoisonPill.getInstance());
jobStatusListener = null;
}
checkpointIdCounter.stop();
// clear and discard all pending checkpoints
for (PendingCheckpoint pending : pendingCheckpoints.values()) {
pending.discard(userClassLoader);
}
pendingCheckpoints.clear();
// clean and discard all successful checkpoints
completedCheckpointStore.discardAllCheckpoints();
onShutdown();
}
} finally {
// Remove shutdown hook to prevent resource leaks, unless this is invoked by the
// shutdown hook itself.
if (shutdownHook != null && shutdownHook != Thread.currentThread()) {
try {
Runtime.getRuntime().removeShutdownHook(shutdownHook);
} catch (IllegalStateException ignored) {
// race, JVM is in shutdown already, we can safely ignore this
} catch (Throwable t) {
LOG.warn("Error unregistering checkpoint coordinator shutdown hook.", t);
}
}
}
}
}
public void stopCheckpointScheduler() {
synchronized (lock) {
triggerRequestQueued = false;
periodicScheduling = false;
if (currentPeriodicTrigger != null) {
currentPeriodicTrigger.cancel();
currentPeriodicTrigger = null;
}
for (PendingCheckpoint p : pendingCheckpoints.values()) {
p.discard(userClassLoader);
}
pendingCheckpoints.clear();
numUnsuccessfulCheckpointsTriggers = 0;
}
}
/**
* Receives an AcknowledgeCheckpoint message and returns whether the message was associated with a
* pending checkpoint.
*
* @param message Checkpoint ack from the task manager
* @return Flag indicating whether the ack'd checkpoint was associated with a pending checkpoint.
* @throws Exception If the checkpoint cannot be added to the completed checkpoint store.
*/
public boolean receiveAcknowledgeMessage(AcknowledgeCheckpoint message) throws Exception {
if (shutdown || message == null) {
return false;
}
if (!job.equals(message.getJob())) {
LOG.error("Received AcknowledgeCheckpoint message for wrong job: {}", message);
return false;
}
final long checkpointId = message.getCheckpointId();
CompletedCheckpoint completed = null;
PendingCheckpoint checkpoint;
// Flag indicating whether the ack message was for a known pending
// checkpoint.
boolean isPendingCheckpoint;
synchronized (lock) {
// we need to check inside the lock for being shutdown as well, otherwise we
// get races and invalid error log messages
if (shutdown) {
return false;
}
checkpoint = pendingCheckpoints.get(checkpointId);
if (checkpoint != null && !checkpoint.isDiscarded()) {
isPendingCheckpoint = true;
if (checkpoint.acknowledgeTask(
message.getTaskExecutionId(),
message.getState(),
message.getStateSize(),
null)) { // TODO: Give KV-state to the acknowledgeTask method
if (checkpoint.isFullyAcknowledged()) {
completed = checkpoint.toCompletedCheckpoint();
completedCheckpointStore.addCheckpoint(completed);
LOG.info(
"Completed checkpoint "
+ checkpointId
+ " (in "
+ completed.getDuration()
+ " ms)");
if (LOG.isDebugEnabled()) {
StringBuilder builder = new StringBuilder();
for (Map.Entry<JobVertexID, TaskState> entry : completed.getTaskStates().entrySet()) {
builder
.append("JobVertexID: ")
.append(entry.getKey())
.append(" {")
.append(entry.getValue())
.append("}");
}
LOG.debug(builder.toString());
}
pendingCheckpoints.remove(checkpointId);
rememberRecentCheckpointId(checkpointId);
dropSubsumedCheckpoints(completed.getTimestamp());
onFullyAcknowledgedCheckpoint(completed);
triggerQueuedRequests();
}
} else {
// checkpoint did not accept message
LOG.error(
"Received duplicate or invalid acknowledge message for checkpoint "
+ checkpointId
+ " , task "
+ message.getTaskExecutionId());
}
} else if (checkpoint != null) {
// this should not happen
throw new IllegalStateException(
"Received message for discarded but non-removed checkpoint " + checkpointId);
} else {
// message is for an unknown checkpoint, or comes too late (checkpoint disposed)
if (recentPendingCheckpoints.contains(checkpointId)) {
isPendingCheckpoint = true;
LOG.warn("Received late message for now expired checkpoint attempt " + checkpointId);
} else {
isPendingCheckpoint = false;
}
}
}
// send the confirmation messages to the necessary targets. we do this here
// to be outside the lock scope
if (completed != null) {
final long timestamp = completed.getTimestamp();
for (ExecutionVertex ev : tasksToCommitTo) {
Execution ee = ev.getCurrentExecutionAttempt();
if (ee != null) {
ExecutionAttemptID attemptId = ee.getAttemptId();
NotifyCheckpointComplete notifyMessage =
new NotifyCheckpointComplete(job, attemptId, checkpointId, timestamp);
ev.sendMessageToCurrentExecution(notifyMessage, ee.getAttemptId());
}
}
statsTracker.onCompletedCheckpoint(completed);
}
return isPendingCheckpoint;
}
/**
* Receives a {@link DeclineCheckpoint} message and returns whether the message was associated
* with a pending checkpoint.
*
* @param message Checkpoint decline from the task manager
* @return Flag indicating whether the declined checkpoint was associated with a pending
* checkpoint.
*/
public boolean receiveDeclineMessage(DeclineCheckpoint message) throws Exception {
if (shutdown || message == null) {
return false;
}
if (!job.equals(message.getJob())) {
LOG.error("Received DeclineCheckpoint message for wrong job: {}", message);
return false;
}
final long checkpointId = message.getCheckpointId();
PendingCheckpoint checkpoint;
// Flag indicating whether the ack message was for a known pending
// checkpoint.
boolean isPendingCheckpoint;
synchronized (lock) {
// we need to check inside the lock for being shutdown as well, otherwise we
// get races and invalid error log messages
if (shutdown) {
return false;
}
checkpoint = pendingCheckpoints.get(checkpointId);
if (checkpoint != null && !checkpoint.isDiscarded()) {
isPendingCheckpoint = true;
LOG.info(
"Discarding checkpoint "
+ checkpointId
+ " because of checkpoint decline from task "
+ message.getTaskExecutionId());
pendingCheckpoints.remove(checkpointId);
checkpoint.discard(userClassLoader);
rememberRecentCheckpointId(checkpointId);
boolean haveMoreRecentPending = false;
Iterator<Map.Entry<Long, PendingCheckpoint>> entries =
pendingCheckpoints.entrySet().iterator();
while (entries.hasNext()) {
PendingCheckpoint p = entries.next().getValue();
if (!p.isDiscarded()
&& p.getCheckpointTimestamp() >= checkpoint.getCheckpointTimestamp()) {
haveMoreRecentPending = true;
break;
}
}
if (!haveMoreRecentPending && !triggerRequestQueued) {
LOG.info("Triggering new checkpoint because of discarded checkpoint " + checkpointId);
triggerCheckpoint(System.currentTimeMillis());
} else if (!haveMoreRecentPending) {
LOG.info(
"Promoting queued checkpoint request because of discarded checkpoint "
+ checkpointId);
triggerQueuedRequests();
}
} else if (checkpoint != null) {
// this should not happen
throw new IllegalStateException(
"Received message for discarded but non-removed checkpoint " + checkpointId);
} else {
// message is for an unknown checkpoint, or comes too late (checkpoint disposed)
if (recentPendingCheckpoints.contains(checkpointId)) {
isPendingCheckpoint = true;
LOG.info(
"Received another decline checkpoint message for now expired checkpoint attempt "
+ checkpointId);
} else {
isPendingCheckpoint = false;
}
}
}
return isPendingCheckpoint;
}
/**
* Triggers a new checkpoint and uses the given timestamp as the checkpoint timestamp.
*
* @param timestamp The timestamp for the checkpoint.
* @param nextCheckpointId The checkpoint ID to use for this checkpoint or <code>-1</code> if the
* checkpoint ID counter should be queried.
*/
public boolean triggerCheckpoint(long timestamp, long nextCheckpointId) throws Exception {
// make some eager pre-checks
synchronized (lock) {
// abort if the coordinator has been shutdown in the meantime
if (shutdown) {
return false;
}
// sanity check: there should never be more than one trigger request queued
if (triggerRequestQueued) {
LOG.warn("Trying to trigger another checkpoint while one was queued already");
return false;
}
// if too many checkpoints are currently in progress, we need to mark that a request is queued
if (pendingCheckpoints.size() >= maxConcurrentCheckpointAttempts) {
triggerRequestQueued = true;
if (currentPeriodicTrigger != null) {
currentPeriodicTrigger.cancel();
currentPeriodicTrigger = null;
}
return false;
}
// make sure the minimum interval between checkpoints has passed
if (lastTriggeredCheckpoint + minPauseBetweenCheckpoints > timestamp) {
if (currentPeriodicTrigger != null) {
currentPeriodicTrigger.cancel();
currentPeriodicTrigger = null;
}
ScheduledTrigger trigger = new ScheduledTrigger();
timer.scheduleAtFixedRate(trigger, minPauseBetweenCheckpoints, baseInterval);
return false;
}
}
// first check if all tasks that we need to trigger are running.
// if not, abort the checkpoint
ExecutionAttemptID[] triggerIDs = new ExecutionAttemptID[tasksToTrigger.length];
for (int i = 0; i < tasksToTrigger.length; i++) {
Execution ee = tasksToTrigger[i].getCurrentExecutionAttempt();
if (ee != null && ee.getState() == ExecutionState.RUNNING) {
triggerIDs[i] = ee.getAttemptId();
} else {
LOG.info(
"Checkpoint triggering task {} is not being executed at the moment. Aborting checkpoint.",
tasksToTrigger[i].getSimpleName());
return false;
}
}
// 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);
for (ExecutionVertex ev : tasksToWaitFor) {
Execution ee = ev.getCurrentExecutionAttempt();
if (ee != null) {
ackTasks.put(ee.getAttemptId(), ev);
} else {
LOG.info(
"Checkpoint acknowledging task {} is not being executed at the moment. Aborting checkpoint.",
ev.getSimpleName());
return false;
}
}
// we will actually trigger this checkpoint!
lastTriggeredCheckpoint = timestamp;
final long checkpointID;
if (nextCheckpointId < 0) {
try {
// this must happen outside the locked scope, because it communicates
// with external services (in HA mode) and may block for a while.
checkpointID = checkpointIdCounter.getAndIncrement();
} catch (Throwable t) {
int numUnsuccessful = ++numUnsuccessfulCheckpointsTriggers;
LOG.warn(
"Failed to trigger checkpoint ("
+ numUnsuccessful
+ " consecutive failed attempts so far)",
t);
return false;
}
} else {
checkpointID = nextCheckpointId;
}
LOG.info("Triggering checkpoint " + checkpointID + " @ " + timestamp);
final PendingCheckpoint checkpoint =
new PendingCheckpoint(job, checkpointID, timestamp, ackTasks);
// schedule the timer that will clean up the expired checkpoints
TimerTask canceller =
new TimerTask() {
@Override
public void run() {
try {
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 " + checkpointID + " expired before completing.");
checkpoint.discard(userClassLoader);
pendingCheckpoints.remove(checkpointID);
rememberRecentCheckpointId(checkpointID);
onCancelCheckpoint(checkpointID);
triggerQueuedRequests();
}
}
} catch (Throwable t) {
LOG.error("Exception while handling checkpoint timeout", t);
}
}
};
try {
// re-acquire the lock
synchronized (lock) {
// since we released the lock in the meantime, we need to re-check
// that the conditions still hold. this is clumsy, but it allows us to
// release the lock in the meantime while calls to external services are
// blocking progress, and still gives us early checks that skip work
// if no checkpoint can happen anyways
if (shutdown) {
return false;
} else if (triggerRequestQueued) {
LOG.warn("Trying to trigger another checkpoint while one was queued already");
return false;
} else if (pendingCheckpoints.size() >= maxConcurrentCheckpointAttempts) {
triggerRequestQueued = true;
if (currentPeriodicTrigger != null) {
currentPeriodicTrigger.cancel();
currentPeriodicTrigger = null;
}
return false;
}
pendingCheckpoints.put(checkpointID, checkpoint);
timer.schedule(canceller, checkpointTimeout);
}
// end of lock scope
// send the messages to the tasks that trigger their checkpoint
for (int i = 0; i < tasksToTrigger.length; i++) {
ExecutionAttemptID id = triggerIDs[i];
TriggerCheckpoint message = new TriggerCheckpoint(job, id, checkpointID, timestamp);
tasksToTrigger[i].sendMessageToCurrentExecution(message, id);
}
numUnsuccessfulCheckpointsTriggers = 0;
return true;
} catch (Throwable t) {
// guard the map against concurrent modifications
synchronized (lock) {
pendingCheckpoints.remove(checkpointID);
}
int numUnsuccessful = ++numUnsuccessfulCheckpointsTriggers;
LOG.warn(
"Failed to trigger checkpoint ("
+ numUnsuccessful
+ " consecutive failed attempts so far)",
t);
if (!checkpoint.isDiscarded()) {
checkpoint.discard(userClassLoader);
}
return false;
}
}
