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本文主要研究一下storm TridentBoltExecutor的finishBatch方法
MasterBatchCoordinator.nextTuple
storm-core-1.2.2-sources.jar!/org/apache/storm/trident/topology/MasterBatchCoordinator.java
public void nextTuple() {
sync();
}
private void sync() {
// note that sometimes the tuples active may be less than max_spout_pending, e.g.
// max_spout_pending = 3
// tx 1, 2, 3 active, tx 2 is acked. there won't be a commit for tx 2 (because tx 1 isn't committed yet),
// and there won't be a batch for tx 4 because there's max_spout_pending tx active
TransactionStatus maybeCommit = _activeTx.get(_currTransaction);
if(maybeCommit!=null && maybeCommit.status == AttemptStatus.PROCESSED) {
maybeCommit.status = AttemptStatus.COMMITTING;
_collector.emit(COMMIT_STREAM_ID, new Values(maybeCommit.attempt), maybeCommit.attempt);
LOG.debug("Emitted on [stream = {}], [tx_status = {}], [{}]", COMMIT_STREAM_ID, maybeCommit, this);
}
if(_active) {
if(_activeTx.size() < _maxTransactionActive) {
Long curr = _currTransaction;
for(int i=0; i<_maxTransactionActive; i++) {
if(!_activeTx.containsKey(curr) && isReady(curr)) {
// by using a monotonically increasing attempt id, downstream tasks
// can be memory efficient by clearing out state for old attempts
// as soon as they see a higher attempt id for a transaction
Integer attemptId = _attemptIds.get(curr);
if(attemptId==null) {
attemptId = 0;
} else {
attemptId++;
}
_attemptIds.put(curr, attemptId);
for(TransactionalState state: _states) {
state.setData(CURRENT_ATTEMPTS, _attemptIds);
}
TransactionAttempt attempt = new TransactionAttempt(curr, attemptId);
final TransactionStatus newTransactionStatus = new TransactionStatus(attempt);
_activeTx.put(curr, newTransactionStatus);
_collector.emit(BATCH_STREAM_ID, new Values(attempt), attempt);
LOG.debug("Emitted on [stream = {}], [tx_attempt = {}], [tx_status = {}], [{}]", BATCH_STREAM_ID, attempt, newTransactionStatus, this);
_throttler.markEvent();
}
curr = nextTransactionId(curr);
}
}
}
}- MasterBatchCoordinator是整个trident的真正的spout，它的nextTuple方法会向TridentSpoutCoordinator向MasterBatchCoordinator.BATCH_STREAM_ID(
$batch)发射tuple
TridentSpoutCoordinator.execute
storm-core-1.2.2-sources.jar!/org/apache/storm/trident/spout/TridentSpoutCoordinator.java
public void execute(Tuple tuple, BasicOutputCollector collector) {
TransactionAttempt attempt = (TransactionAttempt) tuple.getValue(0);
if(tuple.getSourceStreamId().equals(MasterBatchCoordinator.SUCCESS_STREAM_ID)) {
_state.cleanupBefore(attempt.getTransactionId());
_coord.success(attempt.getTransactionId());
} else {
long txid = attempt.getTransactionId();
Object prevMeta = _state.getPreviousState(txid);
Object meta = _coord.initializeTransaction(txid, prevMeta, _state.getState(txid));
_state.overrideState(txid, meta);
collector.emit(MasterBatchCoordinator.BATCH_STREAM_ID, new Values(attempt, meta));
}
}- TridentSpoutCoordinator接收MasterBatchCoordinator在MasterBatchCoordinator.BATCH_STREAM_ID(
$batch)发过来的tuple，然后向包装用户spout的TridentBoltExecutor发送batch指令
TridentBoltExecutor(TridentSpoutExecutor)
storm-core-1.2.2-sources.jar!/org/apache/storm/trident/topology/TridentBoltExecutor.java
public void execute(Tuple tuple) {
if(TupleUtils.isTick(tuple)) {
long now = System.currentTimeMillis();
if(now - _lastRotate > _messageTimeoutMs) {
_batches.rotate();
_lastRotate = now;
}
return;
}
String batchGroup = _batchGroupIds.get(tuple.getSourceGlobalStreamId());
if(batchGroup==null) {
// this is so we can do things like have simple DRPC that doesn't need to use batch processing
_coordCollector.setCurrBatch(null);
_bolt.execute(null, tuple);
_collector.ack(tuple);
return;
}
IBatchID id = (IBatchID) tuple.getValue(0);
//get transaction id
//if it already exists and attempt id is greater than the attempt there
TrackedBatch tracked = (TrackedBatch) _batches.get(id.getId());
// if(_batches.size() > 10 && _context.getThisTaskIndex() == 0) {
// System.out.println("Received in " + _context.getThisComponentId() + " " + _context.getThisTaskIndex()
// + " (" + _batches.size() + ")" +
// "\ntuple: " + tuple +
// "\nwith tracked " + tracked +
// "\nwith id " + id +
// "\nwith group " + batchGroup
// + "\n");
//
// }
//System.out.println("Num tracked: " + _batches.size() + " " + _context.getThisComponentId() + " " + _context.getThisTaskIndex());
// this code here ensures that only one attempt is ever tracked for a batch, so when
// failures happen you don't get an explosion in memory usage in the tasks
if(tracked!=null) {
if(id.getAttemptId() > tracked.attemptId) {
_batches.remove(id.getId());
tracked = null;
} else if(id.getAttemptId() < tracked.attemptId) {
// no reason to try to execute a previous attempt than we've already seen
return;
}
}
if(tracked==null) {
tracked = new TrackedBatch(new BatchInfo(batchGroup, id, _bolt.initBatchState(batchGroup, id)), _coordConditions.get(batchGroup), id.getAttemptId());
_batches.put(id.getId(), tracked);
}
_coordCollector.setCurrBatch(tracked);
//System.out.println("TRACKED: " + tracked + " " + tuple);
TupleType t = getTupleType(tuple, tracked);
if(t==TupleType.COMMIT) {
tracked.receivedCommit = true;
checkFinish(tracked, tuple, t);
} else if(t==TupleType.COORD) {
int count = tuple.getInteger(1);
tracked.reportedTasks++;
tracked.expectedTupleCount+=count;
checkFinish(tracked, tuple, t);
} else {
tracked.receivedTuples++;
boolean success = true;
try {
_bolt.execute(tracked.info, tuple);
if(tracked.condition.expectedTaskReports==0) {
success = finishBatch(tracked, tuple);
}
} catch(FailedException e) {
failBatch(tracked, e);
}
if(success) {
_collector.ack(tuple);
} else {
_collector.fail(tuple);
}
}
_coordCollector.setCurrBatch(null);
}
private boolean finishBatch(TrackedBatch tracked, Tuple finishTuple) {
boolean success = true;
try {
_bolt.finishBatch(tracked.info);
String stream = COORD_STREAM(tracked.info.batchGroup);
for(Integer task: tracked.condition.targetTasks) {
_collector.emitDirect(task, stream, finishTuple, new Values(tracked.info.batchId, Utils.get(tracked.taskEmittedTuples, task, 0)));
}
if(tracked.delayedAck!=null) {
_collector.ack(tracked.delayedAck);
tracked.delayedAck = null;
}
} catch(FailedException e) {
failBatch(tracked, e);
success = false;
}
_batches.remove(tracked.info.batchId.getId());
return success;
}- TridentBoltExecutor.execute方法，首先会创建并初始化TrackedBatch(
如果TrackedBatch不存在的话)，之后接收到batch指令的时候，对tracked.receivedTuple累加，然后调用_bolt.execute(tracked.info, tuple) - 对于spout来说，这里的_bolt是TridentSpoutExecutor，它的execute方法会往下游的TridentBoltExecutor发射一个batch的tuples；由于spout的expectedTaskReports==0，所以这里在调用完TridentSpoutExecutor发射batch的tuples时，它就立马调用finishBatch
- finishBatch操作，这里会通过COORD_STREAM往下游的TridentBoltExecutor发射[id,count]数据，告知下游TridentBoltExecutor说它一共发射了多少tuples
TridentBoltExecutor(SubtopologyBolt)
storm-core-1.2.2-sources.jar!/org/apache/storm/trident/topology/TridentBoltExecutor.java
@Override
public void execute(Tuple tuple) {
if(TupleUtils.isTick(tuple)) {
long now = System.currentTimeMillis();
if(now - _lastRotate > _messageTimeoutMs) {
_batches.rotate();
_lastRotate = now;
}
return;
}
String batchGroup = _batchGroupIds.get(tuple.getSourceGlobalStreamId());
if(batchGroup==null) {
// this is so we can do things like have simple DRPC that doesn't need to use batch processing
_coordCollector.setCurrBatch(null);
_bolt.execute(null, tuple);
_collector.ack(tuple);
return;
}
IBatchID id = (IBatchID) tuple.getValue(0);
//get transaction id
//if it already exists and attempt id is greater than the attempt there
TrackedBatch tracked = (TrackedBatch) _batches.get(id.getId());
// if(_batches.size() > 10 && _context.getThisTaskIndex() == 0) {
// System.out.println("Received in " + _context.getThisComponentId() + " " + _context.getThisTaskIndex()
// + " (" + _batches.size() + ")" +
// "\ntuple: " + tuple +
// "\nwith tracked " + tracked +
// "\nwith id " + id +
// "\nwith group " + batchGroup
// + "\n");
//
// }
//System.out.println("Num tracked: " + _batches.size() + " " + _context.getThisComponentId() + " " + _context.getThisTaskIndex());
// this code here ensures that only one attempt is ever tracked for a batch, so when
// failures happen you don't get an explosion in memory usage in the tasks
if(tracked!=null) {
if(id.getAttemptId() > tracked.attemptId) {
_batches.remove(id.getId());
tracked = null;
} else if(id.getAttemptId() < tracked.attemptId) {
// no reason to try to execute a previous attempt than we've already seen
return;
}
}
if(tracked==null) {
tracked = new TrackedBatch(new BatchInfo(batchGroup, id, _bolt.initBatchState(batchGroup, id)), _coordConditions.get(batchGroup), id.getAttemptId());
_batches.put(id.getId(), tracked);
}
_coordCollector.setCurrBatch(tracked);
//System.out.println("TRACKED: " + tracked + " " + tuple);
TupleType t = getTupleType(tuple, tracked);
if(t==TupleType.COMMIT) {
tracked.receivedCommit = true;
checkFinish(tracked, tuple, t);
} else if(t==TupleType.COORD) {
int count = tuple.getInteger(1);
tracked.reportedTasks++;
tracked.expectedTupleCount+=count;
checkFinish(tracked, tuple, t);
} else {
tracked.receivedTuples++;
boolean success = true;
try {
_bolt.execute(tracked.info, tuple);
if(tracked.condition.expectedTaskReports==0) {
success = finishBatch(tracked, tuple);
}
} catch(FailedException e) {
failBatch(tracked, e);
}
if(success) {
_collector.ack(tuple);
} else {
_collector.fail(tuple);
}
}
_coordCollector.setCurrBatch(null);
}
private void checkFinish(TrackedBatch tracked, Tuple tuple, TupleType type) {
if(tracked.failed) {
failBatch(tracked);
_collector.fail(tuple);
return;
}
CoordCondition cond = tracked.condition;
boolean delayed = tracked.delayedAck==null &&
(cond.commitStream!=null && type==TupleType.COMMIT
|| cond.commitStream==null);
if(delayed) {
tracked.delayedAck = tuple;
}
boolean failed = false;
if(tracked.receivedCommit && tracked.reportedTasks == cond.expectedTaskReports) {
if(tracked.receivedTuples == tracked.expectedTupleCount) {
finishBatch(tracked, tuple);
} else {
//TODO: add logging that not all tuples were received
failBatch(tracked);
_collector.fail(tuple);
failed = true;
}
}
if(!delayed && !failed) {
_collector.ack(tuple);
}
}
private boolean finishBatch(TrackedBatch tracked, Tuple finishTuple) {
boolean success = true;
try {
_bolt.finishBatch(tracked.info);
String stream = COORD_STREAM(tracked.info.batchGroup);
for(Integer task: tracked.condition.targetTasks) {
_collector.emitDirect(task, stream, finishTuple, new Values(tracked.info.batchId, Utils.get(tracked.taskEmittedTuples, task, 0)));
}
if(tracked.delayedAck!=null) {
_collector.ack(tracked.delayedAck);
tracked.delayedAck = null;
}
} catch(FailedException e) {
failBatch(tracked, e);
success = false;
}
_batches.remove(tracked.info.batchId.getId());
return success;
}- TridentBoltExecutor(
SubtopologyBolt)是spout下游的bolt，它的_bolt是SubtopologyBolt，而且它的tracked.condition.expectedTaskReports不为0，因而它是在接收到TupleType.COORD的tuple的时候，才进行checkFinish操作(这里先忽略TupleType.COMMIT类型) - 由于BoltExecutor是使用Utils.asyncLoop来挨个消费receiveQueue的数据的，而且emitBatch的时候也是挨个接收batch的tuples，最后再接收到TridentBoltExecutor(
TridentSpoutExecutor)在finishBatch的时候通过COORD_STREAM发过来的[id,count]的tuple(注意这里的COORD_STREAM是分发给每个task的，如果TridentBoltExecutor有多个parallel，则他们是按各自的task来接收的) - 所以TridentBoltExecutor(
SubtopologyBolt)先挨个处理每个tuple，处理完之后才轮到TupleType.COORD这个tuple，然后触发checkFinish操作；在没有commitStream的情况下，tracked.receivedCommit默认为true，因而这里只要检测收到的tuples与应收的tuples数一致，就执行_bolt.finishBatch操作完成一个batch，然后再往它的下游TridentBoltExecutor发射它应收的[id,count]的tuple
小结
- 对于trident来说，真正的spout是MasterBatchCoordinator，它的nextTuple会触发batch的发送，它将batch指令发送给TridentSpoutCoordinator，而TridentSpoutCoordinator将触发TridentBoltExecutor(
TridentSpoutExecutor)的execute方法，进而触发ITridentSpout的emitter的emitBatch，从而发送一个batch的数据 - TridentBoltExecutor(
TridentSpoutExecutor)的expectedTaskReports==0，它在调用完TridentSpoutExecutor发射batch的tuples时，就立马调用finishBatch操作，通过COORD_STREAM往下游的TridentBoltExecutor发射[id,count]数据，告知下游TridentBoltExecutor说它一共发射了多少tuples - spout的下游bolt为TridentBoltExecutor(
SubtopologyBolt)，它的tracked.condition.expectedTaskReports不为0，因而它是在接收到TupleType.COORD的tuple的时候，才进行checkFinish操作(这里先忽略TupleType.COMMIT类型)，由于spout是先执行emitBatch操作再最后finishBatch发送[id,count]数据，正常情况下按顺序进入到TridentBoltExecutor(SubtopologyBolt)的receiveQueue队列，然后TridentBoltExecutor(SubtopologyBolt)挨个消费tuple，调用SubtopologyBolt.execute，最后再处理[id,count]数据，触发checkFinish操作，只要检测收到的tuples与应收的tuples数一致，就执行SubtopologyBolt.finishBatch操作完成这个batch，然后再往它的下游TridentBoltExecutor发射它应收的[id,count]的tuple
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