tillrohrmann commented on a change in pull request #11313: [FLINK-16373] Make
JobManagerLeaderListener thread safe
URL: https://github.com/apache/flink/pull/11313#discussion_r393706944
##########
File path:
flink-runtime/src/main/java/org/apache/flink/runtime/taskexecutor/JobLeaderService.java
##########
@@ -251,90 +254,83 @@ private JobManagerLeaderListener(JobID jobId) {
}
public void stop() {
- stopped = true;
+ synchronized (lock) {
+ stopped = true;
- if (rpcConnection != null) {
- rpcConnection.close();
+ if (rpcConnection != null) {
+ rpcConnection.close();
+ }
}
}
public void reconnect() {
- if (stopped) {
- LOG.debug("Cannot reconnect because the
JobManagerLeaderListener has already been stopped.");
- } else {
- final RegisteredRpcConnection<JobMasterId,
JobMasterGateway, JMTMRegistrationSuccess> currentRpcConnection = rpcConnection;
-
- if (currentRpcConnection != null) {
- if (currentRpcConnection.isConnected())
{
-
- if
(currentRpcConnection.tryReconnect()) {
- // double check for
concurrent stop operation
- if (stopped) {
-
currentRpcConnection.close();
- }
- } else {
- LOG.debug("Could not
reconnect to the JobMaster {}.", currentRpcConnection.getTargetAddress());
- }
+ synchronized (lock) {
+ if (stopped) {
+ LOG.debug("Cannot reconnect because the
JobManagerLeaderListener has already been stopped.");
+ } else {
+ if (rpcConnection != null) {
+ Preconditions.checkState(
+
rpcConnection.tryReconnect(),
+ "Illegal concurrent
modification of the JobManagerLeaderListener rpc connection.");
} else {
- LOG.debug("Ongoing registration
to JobMaster {}.", currentRpcConnection.getTargetAddress());
+ LOG.debug("Cannot reconnect to
an unknown JobMaster.");
}
- } else {
- LOG.debug("Cannot reconnect to an
unknown JobMaster.");
}
}
}
@Override
- public void notifyLeaderAddress(final @Nullable String
leaderAddress, final @Nullable UUID leaderId) {
- if (stopped) {
- LOG.debug("{}'s leader retrieval listener
reported a new leader for job {}. " +
- "However, the service is no longer
running.", JobLeaderService.class.getSimpleName(), jobId);
- } else {
- final JobMasterId jobMasterId =
JobMasterId.fromUuidOrNull(leaderId);
-
- LOG.debug("New leader information for job {}.
Address: {}, leader id: {}.",
- jobId, leaderAddress, jobMasterId);
-
- if (leaderAddress == null ||
leaderAddress.isEmpty()) {
- // the leader lost leadership but there
is no other leader yet.
- if (rpcConnection != null) {
- rpcConnection.close();
- }
+ public void notifyLeaderAddress(@Nullable final String
leaderAddress, @Nullable final UUID leaderId) {
+ Optional<JobMasterId> jobManagerLostLeadership =
Optional.empty();
-
jobLeaderListener.jobManagerLostLeadership(jobId, currentJobMasterId);
-
- currentJobMasterId = jobMasterId;
+ synchronized (lock) {
+ if (stopped) {
+ LOG.debug("{}'s leader retrieval
listener reported a new leader for job {}. " +
+ "However, the service is no
longer running.", JobLeaderService.class.getSimpleName(), jobId);
} else {
- currentJobMasterId = jobMasterId;
+ final JobMasterId jobMasterId =
JobMasterId.fromUuidOrNull(leaderId);
- if (rpcConnection != null) {
- // check if we are already
trying to connect to this leader
- if
(!Objects.equals(jobMasterId, rpcConnection.getTargetLeaderId())) {
+ LOG.debug("New leader information for
job {}. Address: {}, leader id: {}.",
+ jobId, leaderAddress,
jobMasterId);
+
+ if (leaderAddress == null ||
leaderAddress.isEmpty()) {
+ // the leader lost leadership
but there is no other leader yet.
+ if (rpcConnection != null) {
rpcConnection.close();
+ }
+ jobManagerLostLeadership =
Optional.of(currentJobMasterId);
+ currentJobMasterId =
jobMasterId;
+ } else {
+ currentJobMasterId =
jobMasterId;
+
+ if (rpcConnection != null) {
+ // check if we are
already trying to connect to this leader
+ if
(!Objects.equals(jobMasterId, rpcConnection.getTargetLeaderId())) {
+
rpcConnection.close();
+
+ rpcConnection =
new JobManagerRegisteredRpcConnection(
+ LOG,
+
leaderAddress,
+
jobMasterId,
+
rpcService.getExecutor());
+ }
+ } else {
rpcConnection = new
JobManagerRegisteredRpcConnection(
LOG,
leaderAddress,
jobMasterId,
rpcService.getExecutor());
}
- } else {
- rpcConnection = new
JobManagerRegisteredRpcConnection(
- LOG,
- leaderAddress,
- jobMasterId,
-
rpcService.getExecutor());
- }
- // double check for a concurrent stop
operation
- if (stopped) {
- rpcConnection.close();
- } else {
LOG.info("Try to register at
job manager {} with leader id {}.", leaderAddress, leaderId);
rpcConnection.start();
}
}
}
+
+ // send callbacks outside of the lock scope
Review comment:
Exactly. Triggering callbacks outside of the lock scope is preferrable
because one does not know what the callback will do. It could happen that it
waits for another lock which could then lead to a deadlock.
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