Re: Review Request 58898: Do not kill non partition aware tasks.

[Megha Sharma]

> On May 10, 2017, 11:24 p.m., Neil Conway wrote:
> > My apologies for the delay in reviewing this.
> > 
> > High-level comments:
> > 
> > (a) Can we improve the description of the problem in the commit summary? It 
> > took me quite a while to figure out what is actually going on here. My 
> > understanding is:
> > 
> > (1) Agent re-registers
> > (2) Master sends `ShutdownFrameworkMessage` for non-PA frameworks on the 
> > agent
> > (3) Master offers agent resources to framework
> > (4) Framework launches new task on agent _before the agent has finished 
> > shutting down the framework_
> > (5) Agent ignores launch task because it believes the framework is still 
> > terminating.
> > 
> > This is a race condition, because if the agent finished shutting down the 
> > framework (in #4) before the launch task was received, there would not be a 
> > problem. Is my understanding correct?
> > 
> > (2) I'd prefer a new unit test that constructs exactly this scenario, 
> > rather than changing existing unit tests.
> > 
> > (3) The new behavior is that the framework will receive `TASK_KILLED` for 
> > any non-PA tasks running on a partitioned agent that re-registers. This 
> > does not seem ideal, because `TASK_KILLED` _normally_ corresponds to a 
> > framework-initiated `killTask` operation.
> > 
> > (4) Thinking out loud, what if a custom executor ignores the `killTask` 
> > request? When shutting down a framework, it seems we forcibly destroy the 
> > container (via `containerizer->destroy()`), if the executor doesn't exit 
> > promptly upon receiving the framework shutdown request. AFAIK we don't have 
> > similar logic for `killTask` requests.
> > 
> > 3 + 4 suggests that maybe we want a different way to terminate the task on 
> > the agent -- let's discuss.
> 
> Megha Sharma wrote:
> Summarizing the 2 approaches we talked about.
> 
> Approach 1: ShutdownFrameworkMessage
> 
> 1. Upon agent re-registration, master will add tasks even for non-PA 
> frameworks on this agent. This is needed by the master to do correct resource 
> accounting and not offer resources already in use on this agent. We need to 
> mutate the TaskState on the Task before adding them to the master's data 
> structures since the TaskState might be non-terminal when the agent sends 
> these tasks with ReregisterSlaveMessage. And the master has already sent 
> TASK_LOST for these tasks to the frameworks so we need to set the TaskState 
> to TASK_LOST so that any future reconciliations with the framework doesn't 
> have this task transitioning from TASK_LOST to TASK_RUNNNG/TASK_STARTING. 
> This is to avoid unnecessary confusion about task state as observed by the 
> framework but indeed this could have happened with non-strict registry as 
> well where the framework can actually receive a non terminal task state 
> update after receiving a TASK_LOST for the same task in the past.
> 
> 2. When the agent re-registers, the master will continue to send a 
> ShutdownFrameworkMessage to the agent to kill the tasks pertaining to non-PA 
> frameworks on the agent as it does today. An additional optional field will 
> be added to the ShutdownFrameworkMessage to indicate whether or not the 
> shutdown was initiated internally.
> 
> 3. During framework shutdown the state of the framework is set to 
> Framework::TERMINATING which prevents it from launching new tasks. Here, 
> since the framework is not really terminating so in order to allow it to 
> launch new tasks, the agent will not set the state to terminating if the 
> ShutdownFrameworkMessage is generated internally.
> 
> 4. The framework shutdown today doesn't generate any status updates which 
> needs to change. The status updates will be sent if the framework shutdown is 
> triggered internally, this is needed to remove the tasks of non-PA frameworks 
> that got added when the agent re-registered (1).
> 
> Approach 2: Do not shutdown non-PA framework when agent re-registers and 
> let the frameworks make the decision on what needs to be done when they 
> receive non-terminal status updates for tasks for which they have already 
> received a TASK_LOST. This hopefully won't break any frameworks since it 
> could have happened in the past with non-strict registry as well and 
> frameworks should be resilient enough to handle this scenario.
> 
> Let me know if I have missed anything. Personally, I am in favor of 
> approach 1 as it seems less catastrophic for the frameworks. What do you 
> think?
> 
> Megha Sharma wrote:
> The proposed solution to fix the race between new task launches and 
> shutdown framework on the agent, was to not kill the non-partition aware 
> tasks when an unreachable agent re-registers with the master. So now as far 
> as Mesos internals are concerned, the tasks from non-partition aware 
> frameworks are to be treated the same way as partition aware tasks and one 
> way to do it cleanly in Mesos was to 

Re: Review Request 58898: Do not kill non partition aware tasks.

[Mesos Reviewbot Windows]

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Bad patch!

Reviews applied: [58898]

Failed command: python support/apply-reviews.py -n -r 58898

Error:
Traceback (most recent call last):
  File "support/apply-reviews.py", line 417, in 
main()
  File "support/apply-reviews.py", line 412, in main
reviewboard(options)
  File "support/apply-reviews.py", line 402, in reviewboard
apply_review(options)
  File "support/apply-reviews.py", line 160, in apply_review
commit_patch(options)
  File "support/apply-reviews.py", line 261, in commit_patch
message.write(data['message'])
UnicodeEncodeError: 'ascii' codec can't encode character u'\u2019' in position 
655: ordinal not in range(128)

Full log: http://mesos-winbot.westus.cloudapp.azure.com/logs/212/console

- Mesos Reviewbot Windows


On Aug. 6, 2017, 4:35 a.m., Megha Sharma wrote:
> 
> ---
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/58898/
> ---
> 
> (Updated Aug. 6, 2017, 4:35 a.m.)
> 
> 
> Review request for mesos, Neil Conway and Jiang Yan Xu.
> 
> 
> Bugs: MESOS-7215
> https://issues.apache.org/jira/browse/MESOS-7215
> 
> 
> Repository: mesos
> 
> 
> Description
> ---
> 
> Master will not kill the tasks for non-Partition aware frameworks
> when an unreachable agent re-registers with the master.
> Master used to send a ShutdownFrameworkMessages to the agent
> to kill the tasks from non partition aware frameworks including the
> ones that are still registered which was problematic because the offer
> from this agent could still go to the same framework which could then
> launch new tasks. The agent would then receive tasks of the same
> framework and ignore them because it thinks the framework is shutting
> down. The framework is not shutting down of course, so from the master
> and the scheduler’s perspective the task is pending in STAGING forever
> until the next agent reregistration, which could happen much later.
> This commit fixes the problem by not shutting down the non-partition
> aware frameworks on such an agent.
> 
> 
> Diffs
> -
> 
>   src/master/http.cpp 959091c8ec03b6ac7bcb5d21b04d2f7d5aff7d54 
>   src/master/master.hpp b802fd153a10f6012cea381f153c28cc78cae995 
>   src/master/master.cpp 7f38a5e21884546d4b4c866ca5918db779af8f99 
>   src/tests/partition_tests.cpp 62a84f797201ccd18b71490949e3130d2b9c3668 
> 
> 
> Diff: https://reviews.apache.org/r/58898/diff/3/
> 
> 
> Testing
> ---
> 
> make check
> 
> 
> Thanks,
> 
> Megha Sharma
> 
>

Re: Review Request 58898: Do not kill non partition aware tasks.

[Megha Sharma]

> On May 10, 2017, 11:24 p.m., Neil Conway wrote:
> > src/master/master.cpp
> > Lines 6034 (patched)
> > 
> >
> > `tasksToKill`

Code changed, not relevant anymore


> On May 10, 2017, 11:24 p.m., Neil Conway wrote:
> > src/master/master.cpp
> > Lines 6057 (patched)
> > 
> >
> > "Keep"

Code changed, not relevant anymore


- Megha


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This is an automatically generated e-mail. To reply, visit:
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On Aug. 6, 2017, 4:35 a.m., Megha Sharma wrote:
> 
> ---
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/58898/
> ---
> 
> (Updated Aug. 6, 2017, 4:35 a.m.)
> 
> 
> Review request for mesos, Neil Conway and Jiang Yan Xu.
> 
> 
> Bugs: MESOS-7215
> https://issues.apache.org/jira/browse/MESOS-7215
> 
> 
> Repository: mesos
> 
> 
> Description
> ---
> 
> Master will not kill the tasks for non-Partition aware frameworks
> when an unreachable agent re-registers with the master.
> Master used to send a ShutdownFrameworkMessages to the agent
> to kill the tasks from non partition aware frameworks including the
> ones that are still registered which was problematic because the offer
> from this agent could still go to the same framework which could then
> launch new tasks. The agent would then receive tasks of the same
> framework and ignore them because it thinks the framework is shutting
> down. The framework is not shutting down of course, so from the master
> and the scheduler’s perspective the task is pending in STAGING forever
> until the next agent reregistration, which could happen much later.
> This commit fixes the problem by not shutting down the non-partition
> aware frameworks on such an agent.
> 
> 
> Diffs
> -
> 
>   src/master/http.cpp 959091c8ec03b6ac7bcb5d21b04d2f7d5aff7d54 
>   src/master/master.hpp b802fd153a10f6012cea381f153c28cc78cae995 
>   src/master/master.cpp 7f38a5e21884546d4b4c866ca5918db779af8f99 
>   src/tests/partition_tests.cpp 62a84f797201ccd18b71490949e3130d2b9c3668 
> 
> 
> Diff: https://reviews.apache.org/r/58898/diff/3/
> 
> 
> Testing
> ---
> 
> make check
> 
> 
> Thanks,
> 
> Megha Sharma
> 
>

Re: Review Request 58898: Do not kill non partition aware tasks.

[Megha Sharma]

> On May 10, 2017, 11:24 p.m., Neil Conway wrote:
> > My apologies for the delay in reviewing this.
> > 
> > High-level comments:
> > 
> > (a) Can we improve the description of the problem in the commit summary? It 
> > took me quite a while to figure out what is actually going on here. My 
> > understanding is:
> > 
> > (1) Agent re-registers
> > (2) Master sends `ShutdownFrameworkMessage` for non-PA frameworks on the 
> > agent
> > (3) Master offers agent resources to framework
> > (4) Framework launches new task on agent _before the agent has finished 
> > shutting down the framework_
> > (5) Agent ignores launch task because it believes the framework is still 
> > terminating.
> > 
> > This is a race condition, because if the agent finished shutting down the 
> > framework (in #4) before the launch task was received, there would not be a 
> > problem. Is my understanding correct?
> > 
> > (2) I'd prefer a new unit test that constructs exactly this scenario, 
> > rather than changing existing unit tests.
> > 
> > (3) The new behavior is that the framework will receive `TASK_KILLED` for 
> > any non-PA tasks running on a partitioned agent that re-registers. This 
> > does not seem ideal, because `TASK_KILLED` _normally_ corresponds to a 
> > framework-initiated `killTask` operation.
> > 
> > (4) Thinking out loud, what if a custom executor ignores the `killTask` 
> > request? When shutting down a framework, it seems we forcibly destroy the 
> > container (via `containerizer->destroy()`), if the executor doesn't exit 
> > promptly upon receiving the framework shutdown request. AFAIK we don't have 
> > similar logic for `killTask` requests.
> > 
> > 3 + 4 suggests that maybe we want a different way to terminate the task on 
> > the agent -- let's discuss.
> 
> Megha Sharma wrote:
> Summarizing the 2 approaches we talked about.
> 
> Approach 1: ShutdownFrameworkMessage
> 
> 1. Upon agent re-registration, master will add tasks even for non-PA 
> frameworks on this agent. This is needed by the master to do correct resource 
> accounting and not offer resources already in use on this agent. We need to 
> mutate the TaskState on the Task before adding them to the master's data 
> structures since the TaskState might be non-terminal when the agent sends 
> these tasks with ReregisterSlaveMessage. And the master has already sent 
> TASK_LOST for these tasks to the frameworks so we need to set the TaskState 
> to TASK_LOST so that any future reconciliations with the framework doesn't 
> have this task transitioning from TASK_LOST to TASK_RUNNNG/TASK_STARTING. 
> This is to avoid unnecessary confusion about task state as observed by the 
> framework but indeed this could have happened with non-strict registry as 
> well where the framework can actually receive a non terminal task state 
> update after receiving a TASK_LOST for the same task in the past.
> 
> 2. When the agent re-registers, the master will continue to send a 
> ShutdownFrameworkMessage to the agent to kill the tasks pertaining to non-PA 
> frameworks on the agent as it does today. An additional optional field will 
> be added to the ShutdownFrameworkMessage to indicate whether or not the 
> shutdown was initiated internally.
> 
> 3. During framework shutdown the state of the framework is set to 
> Framework::TERMINATING which prevents it from launching new tasks. Here, 
> since the framework is not really terminating so in order to allow it to 
> launch new tasks, the agent will not set the state to terminating if the 
> ShutdownFrameworkMessage is generated internally.
> 
> 4. The framework shutdown today doesn't generate any status updates which 
> needs to change. The status updates will be sent if the framework shutdown is 
> triggered internally, this is needed to remove the tasks of non-PA frameworks 
> that got added when the agent re-registered (1).
> 
> Approach 2: Do not shutdown non-PA framework when agent re-registers and 
> let the frameworks make the decision on what needs to be done when they 
> receive non-terminal status updates for tasks for which they have already 
> received a TASK_LOST. This hopefully won't break any frameworks since it 
> could have happened in the past with non-strict registry as well and 
> frameworks should be resilient enough to handle this scenario.
> 
> Let me know if I have missed anything. Personally, I am in favor of 
> approach 1 as it seems less catastrophic for the frameworks. What do you 
> think?
> 
> Megha Sharma wrote:
> The proposed solution to fix the race between new task launches and 
> shutdown framework on the agent, was to not kill the non-partition aware 
> tasks when an unreachable agent re-registers with the master. So now as far 
> as Mesos internals are concerned, the tasks from non-partition aware 
> frameworks are to be treated the same way as partition aware tasks and one 
> way to do it cleanly in Mesos was to 

Re: Review Request 58898: Do not kill non partition aware tasks.

[Megha Sharma]

---
This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/58898/
---

(Updated Aug. 6, 2017, 4:35 a.m.)


Review request for mesos, Neil Conway and Jiang Yan Xu.


Summary (updated)
-

Do not kill non partition aware tasks.


Bugs: MESOS-7215
https://issues.apache.org/jira/browse/MESOS-7215


Repository: mesos


Description (updated)
---

Master will not kill the tasks for non-Partition aware frameworks
when an unreachable agent re-registers with the master.
Master used to send a ShutdownFrameworkMessages to the agent
to kill the tasks from non partition aware frameworks including the
ones that are still registered which was problematic because the offer
from this agent could still go to the same framework which could then
launch new tasks. The agent would then receive tasks of the same
framework and ignore them because it thinks the framework is shutting
down. The framework is not shutting down of course, so from the master
and the scheduler’s perspective the task is pending in STAGING forever
until the next agent reregistration, which could happen much later.
This commit fixes the problem by not shutting down the non-partition
aware frameworks on such an agent.


Diffs (updated)
-

  src/master/http.cpp 959091c8ec03b6ac7bcb5d21b04d2f7d5aff7d54 
  src/master/master.hpp b802fd153a10f6012cea381f153c28cc78cae995 
  src/master/master.cpp 7f38a5e21884546d4b4c866ca5918db779af8f99 
  src/tests/partition_tests.cpp 62a84f797201ccd18b71490949e3130d2b9c3668 


Diff: https://reviews.apache.org/r/58898/diff/3/

Changes: https://reviews.apache.org/r/58898/diff/2-3/


Testing
---

make check


Thanks,

Megha Sharma