Hi Encho, thanks a lot for reporting this issue. The problem arises whenever the old leader maintains the connection to ZooKeeper. If this is the case, then ephemeral nodes which we create to protect against faulty delete operations are not removed and consequently the new leader is not able to delete the persisted job graph. So one thing to check is whether the old JM still has an open connection to ZooKeeper. The next thing to check is the session timeout of your ZooKeeper cluster. If you stop the job within the session timeout, then it is also not guaranteed that ZooKeeper has detected that the ephemeral nodes of the old JM must be deleted. In order to understand this better it would be helpful if you could tell us the timing of the different actions.
Cheers, Till On Tue, Aug 28, 2018 at 8:17 AM vino yang <yanghua1...@gmail.com> wrote: > Hi Encho, > > A temporary solution can be used to determine if it has been cleaned up by > monitoring the specific JobID under Zookeeper's "/jobgraph". > Another solution, modify the source code, rudely modify the cleanup mode > to the synchronous form, but the flink operation Zookeeper's path needs to > obtain the corresponding lock, so it is dangerous to do so, and it is not > recommended. > I think maybe this problem can be solved in the next version. It depends > on Till. > > Thanks, vino. > > Encho Mishinev <encho.mishi...@gmail.com> 于2018年8月28日周二 下午1:17写道： > >> Thank you very much for the info! Will keep track of the progress. >> >> In the meantime is there any viable workaround? It seems like HA doesn't >> really work due to this bug. >> >> On Tue, Aug 28, 2018 at 4:52 AM vino yang <yanghua1...@gmail.com> wrote: >> >>> About some implementation mechanisms. >>> Flink uses Zookeeper to store JobGraph (Job's description information >>> and metadata) as a basis for Job recovery. >>> However, previous implementations may cause this information to not be >>> properly cleaned up because it is asynchronously deleted by a background >>> thread. >>> >>> Thanks, vino. >>> >>> vino yang <yanghua1...@gmail.com> 于2018年8月28日周二 上午9:49写道： >>> >>>> Hi Encho, >>>> >>>> This is a problem already known to the Flink community, you can track >>>> its progress through FLINK-10011[1], and currently Till is fixing this >>>> issue. >>>> >>>> [1]: https://issues.apache.org/jira/browse/FLINK-10011 >>>> >>>> Thanks, vino. >>>> >>>> Encho Mishinev <encho.mishi...@gmail.com> 于2018年8月27日周一 下午10:13写道： >>>> >>>>> I am running Flink 1.5.3 with two job managers and two task managers >>>>> in Kubernetes along with HDFS and Zookeeper in high-availability mode. >>>>> >>>>> My problem occurs after the following actions: >>>>> - Upload a .jar file to jobmanager-1 >>>>> - Run a streaming job from the jar on jobmanager-1 >>>>> - Wait for 1 or 2 checkpoints to succeed >>>>> - Kill pod of jobmanager-1 >>>>> After a short delay, jobmanager-2 takes leadership and correctly >>>>> restores the job and continues it >>>>> - Stop job from jobmanager-2 >>>>> >>>>> At this point all seems well, but the problem is that jobmanager-2 >>>>> does not clean up anything that was left from jobmanager-1. This means >>>>> that >>>>> both in HDFS and in Zookeeper remain job graphs, which later on obstruct >>>>> any work of both managers as after any reset they unsuccessfully try to >>>>> restore a non-existent job and fail over and over again. >>>>> >>>>> I am quite certain that jobmanager-2 does not know about any of >>>>> jobmanager-1’s files since the Zookeeper logs reveal that it tries to >>>>> duplicate job folders: >>>>> >>>>> 2018-08-27 13:11:00,038 [myid:] - INFO [ProcessThread(sid:0 >>>>> cport:2181)::PrepRequestProcessor@648] - Got user-level >>>>> KeeperException when processing sessionid:0x1657aa15e480033 type:create >>>>> cxid:0x46 zxid:0x1ab txntype:-1 reqpath:n/a Error >>>>> Path:/flink/default/jobgraphs/83bfa359ca59ce1d4635e18e16651e15/bbb259fd-7826-4950-bc7c-c2be23346c77 >>>>> Error:KeeperErrorCode = NodeExists for >>>>> /flink/default/jobgraphs/83bfa359ca59ce1d4635e18e16651e15/bbb259fd-7826-4950-bc7c-c2be23346c77 >>>>> >>>>> 2018-08-27 13:11:02,296 [myid:] - INFO [ProcessThread(sid:0 >>>>> cport:2181)::PrepRequestProcessor@648] - Got user-level >>>>> KeeperException when processing sessionid:0x1657aa15e480033 type:create >>>>> cxid:0x5c zxid:0x1ac txntype:-1 reqpath:n/a Error >>>>> Path:/flink/default/checkpoint-counter/83bfa359ca59ce1d4635e18e16651e15 >>>>> Error:KeeperErrorCode = NodeExists for >>>>> /flink/default/checkpoint-counter/83bfa359ca59ce1d4635e18e16651e15 >>>>> >>>>> Also jobmanager-2 attempts to delete the jobgraphs folder in Zookeeper >>>>> when the job is stopped, but fails since there are leftover files in it >>>>> from jobmanager-1: >>>>> >>>>> 2018-08-27 13:12:13,406 [myid:] - INFO [ProcessThread(sid:0 >>>>> cport:2181)::PrepRequestProcessor@648] - Got user-level >>>>> KeeperException when processing sessionid:0x1657aa15e480033 type:delete >>>>> cxid:0xa8 zxid:0x1bd txntype:-1 reqpath:n/a Error >>>>> Path:/flink/default/jobgraphs/83bfa359ca59ce1d4635e18e16651e15 >>>>> Error:KeeperErrorCode = Directory not empty for >>>>> /flink/default/jobgraphs/83bfa359ca59ce1d4635e18e16651e15 >>>>> >>>>> I’ve noticed that when restoring the job, it seems like jobmanager-2 >>>>> does not get anything more than jobID, while it perhaps needs some >>>>> metadata? Here is the log that seems suspicious to me: >>>>> >>>>> 2018-08-27 13:09:18,113 INFO >>>>> org.apache.flink.runtime.jobmanager.ZooKeeperSubmittedJobGraphStore - >>>>> Recovered SubmittedJobGraph(83bfa359ca59ce1d4635e18e16651e15, null). >>>>> >>>>> All other logs seem fine in jobmanager-2, it doesn’t seem to be aware >>>>> that it’s overwriting anything or not deleting properly. >>>>> >>>>> My question is - what is the intended way for the job managers to >>>>> correctly exchange metadata in HA mode and why is it not working for me? >>>>> >>>>> Thanks in advance! >>>> >>>>
