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From Maxim Khutornenko <ma...@apache.org>
Subject Re: Review Request 51763: Batching writes - Part 2 (of 3): Converting cron jobs to use BatchWorker.
Date Tue, 13 Sep 2016 23:14:51 GMT

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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/51763/
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(Updated Sept. 13, 2016, 11:14 p.m.)


Review request for Aurora, Joshua Cohen, Stephan Erb, and Zameer Manji.


Changes
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Rebased over 51759.


Repository: aurora


Description
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This is the second part of the `BatchWorker` conversion work that moves cron jobs to use non-blocking
kill followups and reduces the number of trigger threads. See https://reviews.apache.org/r/51759
for more background on the `BatchWorker`.

#####Problem
The current implementation of the cron scheduling relies on a large number of threads (`cron_scheduler_num_threads`=100)
to support cron triggering and killing existing tasks according to `KILL_EXISTING` collision
policy. This creates large spikes of activities at synchronized intervals as users tend to
schedule their cron runs around similar schedules. Moreover, the current implementation re-acquires
write locks multiple times to deliver on `KILL_EXISTING` policy. 

#####Remediation
Trigger level batching is still done in a blocking way but multiple cron triggers may be bundled
together to share the same write transaction. Any followups, however, are performed in a non-blocking
way by relying on a `BatchWorker.executeWithReplay()` and the `BatchWorkCompleted` notification.
In order to still ensure non-concurrent execution of a given job key trigger, a token (job
key) is saved within the trigger itself. A concurrent trigger will bail if a kill followup
is still in progress (token is set AND no entry in `killFollowups` set exists yet).

#####Results
The above approach allowed reducing the number of cron threads to 10 and likely can be reduced
even further. See https://reviews.apache.org/r/51759 for the lock contention results.


Diffs (updated)
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  commons/src/main/java/org/apache/aurora/common/util/BackoffHelper.java 8e73dd9ebc43e06f696bbdac4d658e4b225e7df7

  commons/src/test/java/org/apache/aurora/common/util/BackoffHelperTest.java bc30990d57f444f7d64805ed85c363f1302736d0

  config/findbugs/excludeFilter.xml fe3f4ca5db1484124af14421a3349950dfec8519 
  src/main/java/org/apache/aurora/scheduler/cron/quartz/AuroraCronJob.java c07551e94f9221b5b21c5dc9715e82caa290c2e8

  src/main/java/org/apache/aurora/scheduler/cron/quartz/CronModule.java 155d702d68367b247dd066f773c662407f0e3b5b

  src/test/java/org/apache/aurora/scheduler/cron/quartz/AuroraCronJobTest.java 5c64ff2994e200b3453603ac5470e8e152cebc55

  src/test/java/org/apache/aurora/scheduler/cron/quartz/CronIT.java 1c0a3fa84874d7bc185b78f13d2664cb4d8dd72f


Diff: https://reviews.apache.org/r/51763/diff/


Testing
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All types of testing including deploying to test and production clusters.


Thanks,

Maxim Khutornenko


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