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From Jordan Ly <jordan....@gmail.com>
Subject Re: Review Request 61804: Fix race condition where rescinds are received but not processed before offer is accepted
Date Tue, 22 Aug 2017 20:33:22 GMT

-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/61804/
-----------------------------------------------------------

(Updated Aug. 22, 2017, 8:33 p.m.)


Review request for Aurora, David McLaughlin, Santhosh Kumar Shanmugham, Stephan Erb, and Zameer
Manji.


Changes
-------

Add additional gauge for explicitly tracking globally banned offer sizes


Bugs: AURORA-1945
    https://issues.apache.org/jira/browse/AURORA-1945


Repository: aurora


Description
-------

The current race condition for offers is possible:
```
1. Scheduler receives an offer and adds it to the executor queue for processing.
2. The executor processes the offer and adds it to the HostOffers list.
3. Scheduler receives a rescind for that offer and adds it to the executor queue for processing.
However, there is a lot of load on the executor so there might be a delay between receiving
the rescind and processing it.
4. Scheduler accepts the offer before the rescind is processed by the executor. This will
result in launching a task with an invalid offer leading to TASK_LOST.
```
The following logs show this in action:

Mesos:
```
I0810 14:33:45.744372 19274 master.cpp:6065] Removing offer OFFER_X with revocable resources...
W0810 14:34:23.640905 19279 master.cpp:3696] Ignoring accept of offer OFFER_X since it is
no longer valid
W0810 14:34:23.640923 19279 master.cpp:3709] ACCEPT call used invalid offers '[ OFFER_X ]':
Offer OFFER_X is no longer valid
I0810 14:34:23.640974 19279 master.cpp:6253] Sending status update TASK_LOST for task TASK_Y
with invalid offers: Offer OFFER_X is no longer valid'
```
Aurora:
```
I0810 14:28:45.676 [SchedulerImpl-0, MesosCallbackHandler$MesosCallbackHandlerImpl] Received
offer: OFFER_X 
I0810 14:34:23.635 [TaskGroupBatchWorker, VersionedSchedulerDriverService] Accepting offer
OFFER_X with ops [LAUNCH] 
I0810 14:34:24.186 [Thread-4471585, MesosCallbackHandler$MesosCallbackHandlerImpl] Received
status update for task TASK_Y in state TASK_LOST from SOURCE_MASTER with REASON_INVALID_OFFERS:
Task launched with invalid offers: Offer_X is no longer valid 
I0810 14:34:32.972 [SchedulerImpl-0, MesosCallbackHandler$MesosCallbackHandlerImpl] Offer
rescinded: OFFER_X
W0810 14:34:32.972 [SchedulerImpl-0, OfferManager$OfferManagerImpl] Failed to cancel offer:
OFFER_X.
``` 
I would like to temporarily ban offers if we receive a rescind but the offer has not yet been
added (ie. still in the executor queue). Then, when we actually process the offer we will
not assign it to tasks since we know it has been rescinded already. When we ban the offer,
we will also add a command to unban the offer to the executor queue so that future offers
will not be affected. This solution should also avoid the race condition fixed in: https://issues.apache.org/jira/browse/AURORA-1933


Diffs (updated)
-----

  src/jmh/java/org/apache/aurora/benchmark/fakes/FakeOfferManager.java 6f2ca35c5d83dde29c24865b4826d4932e96da80

  src/main/java/org/apache/aurora/scheduler/mesos/MesosCallbackHandler.java 2a42cac651729b8edec839c86ce406f76b17f810

  src/main/java/org/apache/aurora/scheduler/offers/OfferManager.java a55f8add763f1d5ffbd964afd6e4615ff0021ea5

  src/main/java/org/apache/aurora/scheduler/state/TaskAssigner.java 25399e4a4b8f290065eacaf1e3ec1a36c131266b

  src/test/java/org/apache/aurora/scheduler/mesos/MesosCallbackHandlerTest.java b5fa1c87e367e65d96d5a8eb0c9f43fd10d08d3e

  src/test/java/org/apache/aurora/scheduler/offers/OfferManagerImplTest.java be02449eee97643b258792127521445a2c7fc0d3

  src/test/java/org/apache/aurora/scheduler/state/FirstFitTaskAssignerTest.java 25c1137920553774c32047088ace34279a71bbda



Diff: https://reviews.apache.org/r/61804/diff/4/

Changes: https://reviews.apache.org/r/61804/diff/3-4/


Testing
-------

`./gradlew test`

Ran `./src/test/sh/org/apache/aurora/e2e/test_end_to_end.sh` successfully.

I will verify this patch on a live cluster as well before submitting.


Thanks,

Jordan Ly


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