org.apache.flink.runtime.checkpoint.PendingCheckpoint Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
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*
* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.flink.runtime.checkpoint;
import org.apache.flink.api.common.JobID;
import org.apache.flink.runtime.checkpoint.savepoint.Savepoint;
import org.apache.flink.runtime.checkpoint.savepoint.SavepointV2;
import org.apache.flink.runtime.executiongraph.ExecutionAttemptID;
import org.apache.flink.runtime.executiongraph.ExecutionVertex;
import org.apache.flink.runtime.jobgraph.OperatorID;
import org.apache.flink.runtime.state.CheckpointMetadataOutputStream;
import org.apache.flink.runtime.state.CheckpointStorageLocation;
import org.apache.flink.runtime.state.CompletedCheckpointStorageLocation;
import org.apache.flink.runtime.state.StateUtil;
import org.apache.flink.util.ExceptionUtils;
import org.apache.flink.util.Preconditions;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.annotation.Nullable;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Executor;
import java.util.concurrent.ScheduledFuture;
import static org.apache.flink.util.Preconditions.checkArgument;
import static org.apache.flink.util.Preconditions.checkNotNull;
import static org.apache.flink.util.Preconditions.checkState;
/**
* A pending checkpoint is a checkpoint that has been started, but has not been
* acknowledged by all tasks that need to acknowledge it. Once all tasks have
* acknowledged it, it becomes a {@link CompletedCheckpoint}.
*
* Note that the pending checkpoint, as well as the successful checkpoint keep the
* state handles always as serialized values, never as actual values.
*/
public class PendingCheckpoint {
/**
* Result of the {@link PendingCheckpoint#acknowledgedTasks} method.
*/
public enum TaskAcknowledgeResult {
SUCCESS, // successful acknowledge of the task
DUPLICATE, // acknowledge message is a duplicate
UNKNOWN, // unknown task acknowledged
DISCARDED // pending checkpoint has been discarded
}
// ------------------------------------------------------------------------
/** The PendingCheckpoint logs to the same logger as the CheckpointCoordinator. */
private static final Logger LOG = LoggerFactory.getLogger(CheckpointCoordinator.class);
private final Object lock = new Object();
private final JobID jobId;
private final long checkpointId;
private final long checkpointTimestamp;
private final Map operatorStates;
private final Map notYetAcknowledgedTasks;
private final List masterState;
/** Set of acknowledged tasks. */
private final Set acknowledgedTasks;
/** The checkpoint properties. */
private final CheckpointProperties props;
/** Target storage location to persist the checkpoint metadata to. */
private final CheckpointStorageLocation targetLocation;
/** The promise to fulfill once the checkpoint has been completed. */
private final CompletableFuture onCompletionPromise;
/** The executor for potentially blocking I/O operations, like state disposal. */
private final Executor executor;
private int numAcknowledgedTasks;
private boolean discarded;
/** Optional stats tracker callback. */
@Nullable
private PendingCheckpointStats statsCallback;
private volatile ScheduledFuture cancellerHandle;
// --------------------------------------------------------------------------------------------
public PendingCheckpoint(
JobID jobId,
long checkpointId,
long checkpointTimestamp,
Map verticesToConfirm,
CheckpointProperties props,
CheckpointStorageLocation targetLocation,
Executor executor) {
checkArgument(verticesToConfirm.size() > 0,
"Checkpoint needs at least one vertex that commits the checkpoint");
this.jobId = checkNotNull(jobId);
this.checkpointId = checkpointId;
this.checkpointTimestamp = checkpointTimestamp;
this.notYetAcknowledgedTasks = checkNotNull(verticesToConfirm);
this.props = checkNotNull(props);
this.targetLocation = checkNotNull(targetLocation);
this.executor = Preconditions.checkNotNull(executor);
this.operatorStates = new HashMap<>();
this.masterState = new ArrayList<>();
this.acknowledgedTasks = new HashSet<>(verticesToConfirm.size());
this.onCompletionPromise = new CompletableFuture<>();
}
// --------------------------------------------------------------------------------------------
// ------------------------------------------------------------------------
// Properties
// ------------------------------------------------------------------------
public JobID getJobId() {
return jobId;
}
public long getCheckpointId() {
return checkpointId;
}
public long getCheckpointTimestamp() {
return checkpointTimestamp;
}
public int getNumberOfNonAcknowledgedTasks() {
return notYetAcknowledgedTasks.size();
}
public int getNumberOfAcknowledgedTasks() {
return numAcknowledgedTasks;
}
public Map getOperatorStates() {
return operatorStates;
}
public boolean isFullyAcknowledged() {
return this.notYetAcknowledgedTasks.isEmpty() && !discarded;
}
public boolean isAcknowledgedBy(ExecutionAttemptID executionAttemptId) {
return !notYetAcknowledgedTasks.containsKey(executionAttemptId);
}
public boolean isDiscarded() {
return discarded;
}
/**
* Checks whether this checkpoint can be subsumed or whether it should always continue, regardless
* of newer checkpoints in progress.
*
* @return True if the checkpoint can be subsumed, false otherwise.
*/
public boolean canBeSubsumed() {
// If the checkpoint is forced, it cannot be subsumed.
return !props.forceCheckpoint();
}
CheckpointProperties getProps() {
return props;
}
/**
* Sets the callback for tracking this pending checkpoint.
*
* @param trackerCallback Callback for collecting subtask stats.
*/
void setStatsCallback(@Nullable PendingCheckpointStats trackerCallback) {
this.statsCallback = trackerCallback;
}
/**
* Sets the handle for the canceller to this pending checkpoint. This method fails
* with an exception if a handle has already been set.
*
* @return true, if the handle was set, false, if the checkpoint is already disposed;
*/
public boolean setCancellerHandle(ScheduledFuture cancellerHandle) {
synchronized (lock) {
if (this.cancellerHandle == null) {
if (!discarded) {
this.cancellerHandle = cancellerHandle;
return true;
} else {
return false;
}
}
else {
throw new IllegalStateException("A canceller handle was already set");
}
}
}
// ------------------------------------------------------------------------
// Progress and Completion
// ------------------------------------------------------------------------
/**
* Returns the completion future.
*
* @return A future to the completed checkpoint
*/
public CompletableFuture getCompletionFuture() {
return onCompletionPromise;
}
public CompletedCheckpoint finalizeCheckpoint() throws IOException {
synchronized (lock) {
checkState(isFullyAcknowledged(), "Pending checkpoint has not been fully acknowledged yet.");
// make sure we fulfill the promise with an exception if something fails
try {
// write out the metadata
final Savepoint savepoint = new SavepointV2(checkpointId, operatorStates.values(), masterState);
final CompletedCheckpointStorageLocation finalizedLocation;
try (CheckpointMetadataOutputStream out = targetLocation.createMetadataOutputStream()) {
Checkpoints.storeCheckpointMetadata(savepoint, out);
finalizedLocation = out.closeAndFinalizeCheckpoint();
}
CompletedCheckpoint completed = new CompletedCheckpoint(
jobId,
checkpointId,
checkpointTimestamp,
System.currentTimeMillis(),
operatorStates,
masterState,
props,
finalizedLocation);
onCompletionPromise.complete(completed);
// to prevent null-pointers from concurrent modification, copy reference onto stack
PendingCheckpointStats statsCallback = this.statsCallback;
if (statsCallback != null) {
// Finalize the statsCallback and give the completed checkpoint a
// callback for discards.
CompletedCheckpointStats.DiscardCallback discardCallback =
statsCallback.reportCompletedCheckpoint(finalizedLocation.getExternalPointer());
completed.setDiscardCallback(discardCallback);
}
// mark this pending checkpoint as disposed, but do NOT drop the state
dispose(false);
return completed;
}
catch (Throwable t) {
onCompletionPromise.completeExceptionally(t);
ExceptionUtils.rethrowIOException(t);
return null; // silence the compiler
}
}
}
/**
* Acknowledges the task with the given execution attempt id and the given subtask state.
*
* @param executionAttemptId of the acknowledged task
* @param operatorSubtaskStates of the acknowledged task
* @param metrics Checkpoint metrics for the stats
* @return TaskAcknowledgeResult of the operation
*/
public TaskAcknowledgeResult acknowledgeTask(
ExecutionAttemptID executionAttemptId,
TaskStateSnapshot operatorSubtaskStates,
CheckpointMetrics metrics) {
synchronized (lock) {
if (discarded) {
return TaskAcknowledgeResult.DISCARDED;
}
final ExecutionVertex vertex = notYetAcknowledgedTasks.remove(executionAttemptId);
if (vertex == null) {
if (acknowledgedTasks.contains(executionAttemptId)) {
return TaskAcknowledgeResult.DUPLICATE;
} else {
return TaskAcknowledgeResult.UNKNOWN;
}
} else {
acknowledgedTasks.add(executionAttemptId);
}
List operatorIDs = vertex.getJobVertex().getOperatorIDs();
int subtaskIndex = vertex.getParallelSubtaskIndex();
long ackTimestamp = System.currentTimeMillis();
long stateSize = 0L;
if (operatorSubtaskStates != null) {
for (OperatorID operatorID : operatorIDs) {
OperatorSubtaskState operatorSubtaskState =
operatorSubtaskStates.getSubtaskStateByOperatorID(operatorID);
// if no real operatorSubtaskState was reported, we insert an empty state
if (operatorSubtaskState == null) {
operatorSubtaskState = new OperatorSubtaskState();
}
OperatorState operatorState = operatorStates.get(operatorID);
if (operatorState == null) {
operatorState = new OperatorState(
operatorID,
vertex.getTotalNumberOfParallelSubtasks(),
vertex.getMaxParallelism());
operatorStates.put(operatorID, operatorState);
}
operatorState.putState(subtaskIndex, operatorSubtaskState);
stateSize += operatorSubtaskState.getStateSize();
}
}
++numAcknowledgedTasks;
// publish the checkpoint statistics
// to prevent null-pointers from concurrent modification, copy reference onto stack
final PendingCheckpointStats statsCallback = this.statsCallback;
if (statsCallback != null) {
// Do this in millis because the web frontend works with them
long alignmentDurationMillis = metrics.getAlignmentDurationNanos() / 1_000_000;
SubtaskStateStats subtaskStateStats = new SubtaskStateStats(
subtaskIndex,
ackTimestamp,
stateSize,
metrics.getSyncDurationMillis(),
metrics.getAsyncDurationMillis(),
metrics.getBytesBufferedInAlignment(),
alignmentDurationMillis);
statsCallback.reportSubtaskStats(vertex.getJobvertexId(), subtaskStateStats);
}
return TaskAcknowledgeResult.SUCCESS;
}
}
/**
* Adds a master state (state generated on the checkpoint coordinator) to
* the pending checkpoint.
*
* @param state The state to add
*/
public void addMasterState(MasterState state) {
checkNotNull(state);
synchronized (lock) {
if (!discarded) {
masterState.add(state);
}
}
}
// ------------------------------------------------------------------------
// Cancellation
// ------------------------------------------------------------------------
/**
* Aborts a checkpoint because it expired (took too long).
*/
public void abortExpired() {
try {
Exception cause = new Exception("Checkpoint expired before completing");
onCompletionPromise.completeExceptionally(cause);
reportFailedCheckpoint(cause);
} finally {
dispose(true);
}
}
/**
* Aborts the pending checkpoint because a newer completed checkpoint subsumed it.
*/
public void abortSubsumed() {
try {
Exception cause = new Exception("Checkpoints has been subsumed");
onCompletionPromise.completeExceptionally(cause);
reportFailedCheckpoint(cause);
if (props.forceCheckpoint()) {
throw new IllegalStateException("Bug: forced checkpoints must never be subsumed");
}
} finally {
dispose(true);
}
}
public void abortDeclined() {
try {
Exception cause = new Exception("Checkpoint was declined (tasks not ready)");
onCompletionPromise.completeExceptionally(cause);
reportFailedCheckpoint(cause);
} finally {
dispose(true);
}
}
/**
* Aborts the pending checkpoint due to an error.
* @param cause The error's exception.
*/
public void abortError(Throwable cause) {
try {
Exception failure = new Exception("Checkpoint failed: " + cause.getMessage(), cause);
onCompletionPromise.completeExceptionally(failure);
reportFailedCheckpoint(failure);
} finally {
dispose(true);
}
}
private void dispose(boolean releaseState) {
synchronized (lock) {
try {
numAcknowledgedTasks = -1;
if (!discarded && releaseState) {
executor.execute(new Runnable() {
@Override
public void run() {
// discard the private states.
// unregistered shared states are still considered private at this point.
try {
StateUtil.bestEffortDiscardAllStateObjects(operatorStates.values());
targetLocation.disposeOnFailure();
} catch (Throwable t) {
LOG.warn("Could not properly dispose the private states in the pending checkpoint {} of job {}.",
checkpointId, jobId, t);
} finally {
operatorStates.clear();
}
}
});
}
} finally {
discarded = true;
notYetAcknowledgedTasks.clear();
acknowledgedTasks.clear();
cancelCanceller();
}
}
}
private void cancelCanceller() {
try {
final ScheduledFuture canceller = this.cancellerHandle;
if (canceller != null) {
canceller.cancel(false);
}
}
catch (Exception e) {
// this code should not throw exceptions
LOG.warn("Error while cancelling checkpoint timeout task", e);
}
}
/**
* Reports a failed checkpoint with the given optional cause.
*
* @param cause The failure cause or null.
*/
private void reportFailedCheckpoint(Exception cause) {
// to prevent null-pointers from concurrent modification, copy reference onto stack
final PendingCheckpointStats statsCallback = this.statsCallback;
if (statsCallback != null) {
long failureTimestamp = System.currentTimeMillis();
statsCallback.reportFailedCheckpoint(failureTimestamp, cause);
}
}
// ------------------------------------------------------------------------
// Utilities
// ------------------------------------------------------------------------
@Override
public String toString() {
return String.format("Pending Checkpoint %d @ %d - confirmed=%d, pending=%d",
checkpointId, checkpointTimestamp, getNumberOfAcknowledgedTasks(), getNumberOfNonAcknowledgedTasks());
}
}