Shanthoosh Venkataraman created SAMZA-1663:
----------------------------------------------
Summary: StreamProcessor fails after reestablishing zookeeper
session.
Key: SAMZA-1663
URL: https://issues.apache.org/jira/browse/SAMZA-1663
Project: Samza
Issue Type: Bug
Reporter: Shanthoosh Venkataraman
Assignee: Shanthoosh Venkataraman
*Problem:*
StreamProcessor fails sporadically after reestablishing the zookeeper session.
*Analysis:*
Currently in ZkJobCoordinator, buffered stale events in the leader stream
processor before a zookeeper session disconnect causes the StreamProcessor to
fail after session reconnect. Consider the following scenario:
A. Leader receives processor change notification from zookeeper.
B. Before it acts on the notification, zookeeper session expiration occurs.
C. Leader stream processor disconnects from the group and joins the group as a
follower.
D. It acts upon the stale events (generated for some non-existent processors),
which ends up killing it.
*Relevant stacktrace:*
As we can see in this case, before the session expiration there are two
processorIds viz [000000001, 000000002]. After the session expiration, alive
processorIds were [000000003, 000000004]. StreamProcessor failed since the
leader tries to generate JobModel based upon stale processorIds [000000001,
000000002] after zookeeper session reconnect.
{code:java}
```
[ZkClient-EventThread-291-127.0.0.1:53447] INFO
org.apache.samza.zk.ZkJobCoordinator - Got new session created event for
processor=0000000001
[ZkClient-EventThread-291-127.0.0.1:53447] INFO
org.apache.samza.zk.ZkJobCoordinator - register zk controller for the new
session
[ZkClient-EventThread-291-127.0.0.1:53447] INFO org.apache.samza.zk.ZkUtils -
Created ephemeral path:
/app-test-app-name-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-test-app-id-e4bb9daa-d00d-452c-bf7d-e9625c8f8193/test-app-name-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-test-app-id-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-coordinationData/processors/0000000004
for processor: svenkata-mn1.linkedin.biz 0000000001 in zookeeper.
[ZkClient-EventThread-291-127.0.0.1:53447] INFO org.apache.samza.zk.ZkUtils -
Found these children - [0000000003, 0000000004]
[ZkClient-EventThread-329-127.0.0.1:53447] WARN org.apache.samza.zk.ZkUtils -
ALLOWING handleDataChanged for ProcessorChangeHandler from wrong generation.
current generation=1; callback generation= 1
[ZkClient-EventThread-329-127.0.0.1:53447] INFO
org.apache.samza.zk.ZkControllerImpl -
ZkControllerImpl::ProcessorChangeHandler::handleChildChange - Path:
/app-test-app-name-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-test-app-id-e4bb9daa-d00d-452c-bf7d-e9625c8f819
3/test-app-name-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-test-app-id-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-coordinationData/processors
Current Children: [0000000003, 0000000004]
[ZkClient-EventThread-329-127.0.0.1:53447] INFO
org.apache.samza.zk.ZkJobCoordinator - ZkJobCoordinator::onProcessorChange -
list of processors changed! List size=2
[ZkClient-EventThread-329-127.0.0.1:53447] INFO
org.apache.samza.zk.ScheduleAfterDebounceTime - Attempting to cancel the future
of action: OnProcessorChange
[ZkClient-EventThread-329-127.0.0.1:53447] INFO
org.apache.samza.zk.ScheduleAfterDebounceTime - Scheduled action:
OnProcessorChange to run after: 30000 milliseconds.
[ZkClient-EventThread-291-127.0.0.1:53447] INFO org.apache.samza.zk.ZkUtils -
Found these children - [0000000003, 0000000004]
[ZkClient-EventThread-291-127.0.0.1:53447] INFO
org.apache.samza.zk.ZkLeaderElector - tryBecomeLeader: index = 1 for
path=/app-test-app-name-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-test-app-id-e4bb9daa-d00d-452c-bf7d-e9625c8f8193/test-app-name-e4bb9daa-d00d-452
c-bf7d-e9625c8f8193-test-app-id-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-coordinationData/processors/0000000004
out of [0000000003, 0000000004]
[ZkClient-EventThread-291-127.0.0.1:53447] INFO
org.apache.samza.zk.ZkLeaderElector - Index = 1 Not eligible to be a leader yet!
[ZkClient-EventThread-291-127.0.0.1:53447] INFO
org.apache.samza.zk.ZkLeaderElector - [Processor-0000000001] Subscribing data
change for 0000000003
[ZkClient-EventThread-291-127.0.0.1:53447] INFO
org.apache.samza.zk.ZkLeaderElector - [Processor-0000000001] Predecessor still
exists. Current subscription is valid. Continuing as non-leader.
[ZkClient-EventThread-291-127.0.0.1:53447] INFO org.apache.samza.zk.ZkUtils -
Current version for zk root node:
/app-test-app-name-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-test-app-id-e4bb9daa-d00d-452c-bf7d-e9625c8f8193/test-app-name-e4bb9daa-d00d-452c-bf7d-e96
25c8f8193-test-app-id-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-coordinationData is
1.0, expected version is 1.0
[ZkClient-EventThread-291-127.0.0.1:53447] INFO org.apache.samza.zk.ZkUtils -
subscribing for jm version change
at:/app-test-app-name-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-test-app-id-e4bb9daa-d00d-452c-bf7d-e9625c8f8193/test-app-name-e4bb9daa-d00d-452c-bf7d
-e9625c8f8193-test-app-id-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-coordinationData/JobModelGeneration/jobModelVersion
[ZkClient-EventThread-291-127.0.0.1:53447] WARN org.apache.samza.zk.ZkUtils -
SKIPPING handleDataChanged for ProcessorChangeHandler from wrong generation.
current generation=1; callback generation= 0
[ZkClient-EventThread-291-127.0.0.1:53447] WARN org.apache.samza.zk.ZkUtils -
SKIPPING handleDataChanged for ZkBarrierChangeHandler from wrong generation.
current generation=1; callback generation= 0
[ZkClient-EventThread-291-127.0.0.1:53447] INFO
org.apache.samza.zk.ZkLeaderElector - [Processor-0000000001] Data deleted on
path
/app-test-app-name-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-test-app-id-e4bb9daa-d00d-452c-bf7d-e9625c8f8193/test-app-name-e4bb9daa-
d00d-452c-bf7d-e9625c8f8193-test-app-id-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-coordinationData/processors/0000000000.
Predecessor went away. So, trying to become leader again...
[ZkClient-EventThread-291-127.0.0.1:53447] WARN org.apache.samza.zk.ZkUtils -
SKIPPING handleDataChanged for PreviousProcessorChangeListener from wrong
generation. curGen=1; cb gen= 0
[ZkClient-EventThread-291-127.0.0.1:53447] WARN org.apache.samza.zk.ZkUtils -
SKIPPING handleDataChanged for ZkJobModelVersionChangeHandler from wrong
generation. curGen=1; cb gen= 0
[ZkClient-EventThread-291-127.0.0.1:53447] INFO
org.apache.samza.zk.ZkJobCoordinator - Got syncconnected event for
processor=0000000001.
[ZkClient-EventThread-291-127.0.0.1:53447] INFO
org.apache.samza.zk.ScheduleAfterDebounceTime - Attempting to cancel the future
of action: ZK_SESSION_ERROR
[debounce-thread-0] INFO org.apache.samza.zk.ZkUtils - Found these children -
[0000000001, 0000000002]
[debounce-thread-0] INFO org.apache.samza.zk.ZkUtils - Found these processorIds
- []
[debounce-thread-0] INFO org.apache.samza.zk.ZkJobCoordinator - Generating new
JobModel with processors: [].
[debounce-thread-0] INFO org.apache.samza.zk.ZkUtils - read the model ver=2
from
/app-test-app-name-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-test-app-id-e4bb9daa-d00d-452c-bf7d-e9625c8f8193/test-app-name-e4bb9daa-d00d-452c-bf7d-e9625c8f8193-test-app-id-e4bb9daa-
d00d-452c-bf7d-e9625c8f8193-coordinationData/JobModelGeneration/jobModels/2
[debounce-thread-0] INFO org.apache.samza.coordinator.JobModelManager$ -
SystemStreamPartitionGrouper
org.apache.samza.container.grouper.stream.GroupByPartition@33169a55 has grouped
the SystemStreamPartitions into 5 tasks with the following taskNames:
[Partition 1, Partition 0, Partition 3, Partition 2, Partition 4]
[debounce-thread-0] ERROR org.apache.samza.zk.ScheduleAfterDebounceTime -
Execution of action: OnProcessorChange failed.
java.lang.IllegalArgumentException: Must have at least one container
at
org.apache.samza.container.grouper.task.GroupByContainerIds.group(GroupByContainerIds.java:66)
at
org.apache.samza.coordinator.JobModelManager$.readJobModel(JobModelManager.scala:208)
at
org.apache.samza.coordinator.JobModelManager.readJobModel(JobModelManager.scala)
at
org.apache.samza.zk.ZkJobCoordinator.generateNewJobModel(ZkJobCoordinator.java:354)
at
org.apache.samza.zk.ZkJobCoordinator.doOnProcessorChange(ZkJobCoordinator.java:241)
at
org.apache.samza.zk.ZkJobCoordinator.lambda$onProcessorChange$1(ZkJobCoordinator.java:225)
at
org.apache.samza.zk.ScheduleAfterDebounceTime.lambda$getScheduleableAction$0(ScheduleAfterDebounceTime.java:153)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
```{code}
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