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[ML] Fix possible race condition when closing an opening job #42506

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Merged
merged 2 commits into from
May 24, 2019
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[ML] Fix possible race condition when closing an opening job #42506

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aa7a409
[ML] Fix possible race condition when closing an opening job
May 24, 2019
2260056
Fix comment
May 24, 2019
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34 changes: 19 additions & 15 deletions ...main/java/org/elasticsearch/xpack/ml/job/process/autodetect/AutodetectProcessManager.java
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Original file line number Diff line number Diff line change
Expand Up @@ -401,16 +401,12 @@ protected void doRun() {
logger.debug("Aborted opening job [{}] as it has been closed", jobId);
return;
}
if (processContext.getState() != ProcessContext.ProcessStateName.NOT_RUNNING) {
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@droberts195 droberts195 May 24, 2019

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This check needs to be done under lock to prevent a close sneaking in after this check but before the open actions are performed.

logger.debug("Cannot open job [{}] when its state is [{}]",
jobId, processContext.getState().getClass().getName());
return;
}

try {
createProcessAndSetRunning(processContext, job, params, closeHandler);
processContext.getAutodetectCommunicator().restoreState(params.modelSnapshot());
setJobState(jobTask, JobState.OPENED);
if (createProcessAndSetRunning(processContext, job, params, closeHandler)) {
processContext.getAutodetectCommunicator().restoreState(params.modelSnapshot());
setJobState(jobTask, JobState.OPENED);
}
} catch (Exception e1) {
// No need to log here as the persistent task framework will log it
try {
Expand Down Expand Up @@ -447,19 +443,25 @@ protected void doRun() {
ElasticsearchMappings::resultsMapping, client, clusterState, resultsMappingUpdateHandler);
}

private void createProcessAndSetRunning(ProcessContext processContext,
Job job,
AutodetectParams params,
BiConsumer<Exception, Boolean> handler) throws IOException {
private boolean createProcessAndSetRunning(ProcessContext processContext,
Job job,
AutodetectParams params,
BiConsumer<Exception, Boolean> handler) throws IOException {
// At this point we lock the process context until the process has been started.
// The reason behind this is to ensure closing the job does not happen before
// the process is started as that can result to the job getting seemingly closed
// but the actual process is hanging alive.
processContext.tryLock();
try {
if (processContext.getState() != ProcessContext.ProcessStateName.NOT_RUNNING) {
logger.debug("Cannot open job [{}] when its state is [{}]",
job.getId(), processContext.getState().getClass().getName());
return false;
}
AutodetectCommunicator communicator = create(processContext.getJobTask(), job, params, handler);
communicator.writeHeader();
processContext.setRunning(communicator);
return true;
} finally {
// Now that the process is running and we have updated its state we can unlock.
// It is important to unlock before we initialize the communicator (ie. load the model state)
Expand Down Expand Up @@ -592,6 +594,8 @@ public void closeJob(JobTask jobTask, boolean restart, String reason) {
try {
if (processContext.setDying() == false) {
logger.debug("Cannot close job [{}] as it has been marked as dying", jobId);
// The only way we can get here is if 2 close requests are made very close together.
// The other close has done the work so it's safe to return here without doing anything.
return;
}

Expand All @@ -605,10 +609,10 @@ public void closeJob(JobTask jobTask, boolean restart, String reason) {
if (communicator == null) {
logger.debug("Job [{}] is being closed before its process is started", jobId);
jobTask.markAsCompleted();
return;
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@droberts195 droberts195 May 24, 2019

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Returning here without removing the entry from processByAllocation is the cause of the eventual filling up to capacity of processByAllocation. It's nasty because jobTask.markAsCompleted() causes the externally visible effects of closing the job to all look as expected. It's only the internal data structure that's left with a spurious entry.

} else {
communicator.close(restart, reason);
}

communicator.close(restart, reason);
processByAllocation.remove(allocationId);
} catch (Exception e) {
// If the close failed because the process has explicitly been killed by us then just pass on that exception
Expand All @@ -628,7 +632,7 @@ public void closeJob(JobTask jobTask, boolean restart, String reason) {
try {
nativeStorageProvider.cleanupLocalTmpStorage(jobTask.getDescription());
} catch (IOException e) {
logger.error(new ParameterizedMessage("[{}]Failed to delete temporary files", jobId), e);
logger.error(new ParameterizedMessage("[{}] Failed to delete temporary files", jobId), e);
}
}

Expand Down