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https://issues.apache.org/jira/browse/SAMZA-1730?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Shanthoosh Venkataraman updated SAMZA-1730:
-------------------------------------------
Description:
Existing StreamProcessor implementation doesn't have state variable to
represent it's current state(if it's in rebalance/shutdown/running state).
Absence of this information leads to following two problems.
- When execution of StreamProcessor.stop() &
JobCoordinatorListener.onNewJobModel() occur concurrently, SamzaContainer might
be still running after StreamProcessor had been stopped(due to interleaved
execution order). Here's a sample execution order:
1. User thread invokes `SamzaContaienr.stop()`.
2. `StreamProcessor.stop()` stops the current running samza
container.
3. Before StreamProcessor stops the ZkJobCoordinator,
ZkJobCoordinator initializes and executes a new SamzaContainer(Due to change in
global processors group).
4. StreamProcessor stops the ZkJobCoordinator.
- When StreamProcessor.stop() & JobCoordinatorListener.jobModelExpired()
execute concurrently, StreamProcessor will not be stopped cleanly.
`paused` is state variable held in SamzaContainer to indicate if
it has been stopped for new JobModel for JobCoordinator(By default `paused` is
set to `false` in `SamzaContainer`). Here's the sample execution order where
this problem will
1. User thread invokes `SamzaContainer.stop()` and triggers
`SamzaContainer.shutdown`. At the point, user thread is waiting for
`onContainerStop(paused=false)`(container stopped callback with paused = false).
2. Before the SamzaContainer is shutdown, debounce thread
invokes `onJobModelExpired` and triggers `SamzaContainer.pause()`.
`SamzaContainer.pause()` sets SamzaContainer local state `paused` to true.
3. SamzaContainer shuts down and triggers the container
shutdown callback: onContainerStop(with paused = true). When paused is set to
true in onContainerStop callback, StreamProcessor shutdown sequence is not
triggered.
4. StreamProcessor would participate in the processor group
coordination activities (as if shutdown was not triggered).
5. LocalApplicationRunner.waitForFinish will block indefinitely.
To solve the above problems, following changes were done to StreamProcessor:
* Add state field to `StreamProcessor` to represent it's current state. Before
performing any StreamProcessor operation, it's current state is checked and
only if it's valid for the operation the the operation is performed.
* Remove the paused state from SamzaContainer and it is covered by the
StreamProcessor state itself.
* Make onJobModelExpired as start state for any custom coordinators.
* Interrupt the container thread on StreamProcessor.stop() if it's running
after shutdown timeout.
* Add tests to verify the behavior in StreamProcessor/LocalApplicationRunner.
was:
Existing StreamProcessor implementation doesn't have state variable to
represent it's current state(if it's in rebalance/shutdown/running state).
Absence of this information leads to following two problems.
- When execution of StreamProcessor.stop() &
JobCoordinatorListener.onNewJobModel() occur concurrently, SamzaContainer might
be still running after StreamProcessor had been stopped(due to interleaved
execution order). Here's sample execution order:
1. User thread invokes `SamzaContaienr.stop()`.
2. `StreamProcessor.stop()` stops the current running samza
container.
3. Before StreamProcessor stops the ZkJobCoordinator,
ZkJobCoordinator initializes and executes a new SamzaContainer(Due to change in
global processors group).
4. StreamProcessor stops the ZkJobCoordinator.
- When StreamProcessor.stop() & JobCoordinatorListener.jobModelExpired()
execute concurrently, StreamProcessor will not be stopped cleanly.
`paused` is state variable held in SamzaContainer to indicate if
it has been paused(By default `paused` is set to `false` in `SamzaContainer`).
Here's the sample execution order where this problem will
1. User thread invokes `SamzaContainer.stop()` and triggers
`SamzaContainer.shutdown`. At the point, user thread is waiting for
`onContainerStop(paused=false)`(container stopped callback with paused = false).
2. Before the SamzaContainer is shutdown, debounce thread
invokes `onJobModelExpired` and triggers `SamzaContainer.pause()`.
`SamzaContainer.pause()` sets SamzaContainer local state `paused` to true.
3. SamzaContainer shuts down and triggers the container
shutdown callback: onContainerStop(with paused = true). When paused is set to
true in onContainerStop callback, StreamProcessor shutdown sequence is not
triggered.
4. StreamProcessor would participate in the processor group
coordination activities (as if shutdown was not triggered).
5. LocalApplicationRunner.waitForFinish will block indefinitely.
To solve the above problems, following changes were done to StreamProcessor:
* Add state field to `StreamProcessor` to represent it's current state. Before
performing any StreamProcessor operation, it's current state is checked and
only if it's valid for the operation the the operation is performed.
* Remove the paused state from SamzaContainer and it is covered by the
StreamProcessor state itself.
* Make onJobModelExpired as start state for any custom coordinators.
* Interrupt the container thread on StreamProcessor.stop() if it's running
after shutdown timeout.
* Add tests to verify the behavior in StreamProcessor/LocalApplicationRunner.
> Add state validations in StreamProcesssor.
> ------------------------------------------
>
> Key: SAMZA-1730
> URL: https://issues.apache.org/jira/browse/SAMZA-1730
> Project: Samza
> Issue Type: Bug
> Reporter: Shanthoosh Venkataraman
> Assignee: Shanthoosh Venkataraman
> Priority: Major
>
> Existing StreamProcessor implementation doesn't have state variable to
> represent it's current state(if it's in rebalance/shutdown/running state).
> Absence of this information leads to following two problems.
> - When execution of StreamProcessor.stop() &
> JobCoordinatorListener.onNewJobModel() occur concurrently, SamzaContainer
> might be still running after StreamProcessor had been stopped(due to
> interleaved execution order). Here's a sample execution order:
> 1. User thread invokes `SamzaContaienr.stop()`.
> 2. `StreamProcessor.stop()` stops the current running samza
> container.
> 3. Before StreamProcessor stops the ZkJobCoordinator,
> ZkJobCoordinator initializes and executes a new SamzaContainer(Due to change
> in global processors group).
> 4. StreamProcessor stops the ZkJobCoordinator.
> - When StreamProcessor.stop() & JobCoordinatorListener.jobModelExpired()
> execute concurrently, StreamProcessor will not be stopped cleanly.
> `paused` is state variable held in SamzaContainer to indicate
> if it has been stopped for new JobModel for JobCoordinator(By default
> `paused` is set to `false` in `SamzaContainer`). Here's the sample execution
> order where this problem will
> 1. User thread invokes `SamzaContainer.stop()` and triggers
> `SamzaContainer.shutdown`. At the point, user thread is waiting for
> `onContainerStop(paused=false)`(container stopped callback with paused =
> false).
> 2. Before the SamzaContainer is shutdown, debounce thread
> invokes `onJobModelExpired` and triggers `SamzaContainer.pause()`.
> `SamzaContainer.pause()` sets SamzaContainer local state `paused` to true.
> 3. SamzaContainer shuts down and triggers the container
> shutdown callback: onContainerStop(with paused = true). When paused is set to
> true in onContainerStop callback, StreamProcessor shutdown sequence is not
> triggered.
> 4. StreamProcessor would participate in the processor group
> coordination activities (as if shutdown was not triggered).
> 5. LocalApplicationRunner.waitForFinish will block
> indefinitely.
> To solve the above problems, following changes were done to StreamProcessor:
> * Add state field to `StreamProcessor` to represent it's current state.
> Before performing any StreamProcessor operation, it's current state is
> checked and only if it's valid for the operation the the operation is
> performed.
> * Remove the paused state from SamzaContainer and it is covered by the
> StreamProcessor state itself.
> * Make onJobModelExpired as start state for any custom coordinators.
> * Interrupt the container thread on StreamProcessor.stop() if it's running
> after shutdown timeout.
> * Add tests to verify the behavior in StreamProcessor/LocalApplicationRunner.
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