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Type:
New Feature
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Status: Open
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Priority:
Major
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Resolution: Unresolved
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Affects Version/s: None
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Fix Version/s: None
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Component/s: Runtime / Coordination
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Labels:None
Strugglers/outlier are tasks that run slower than most of the all tasks in a Batch Job, this somehow impact job latency, as pretty much this straggler will be in the critical path of the job and become as the bottleneck.
Tasks may be slow for various reasons, including hardware degradation, or software mis-configuration, or noise neighboring. It's hard for JM to predict the runtime.
To reduce the overhead of strugglers, other system such as Hadoop/Tez, Spark has speculative execution. Speculative execution is a health-check procedure that checks for tasks to be speculated, i.e. running slower in a ExecutionJobVertex than the median of all successfully completed tasks in that EJV, Such slow tasks will be re-submitted to another TM. It will not stop the slow tasks, but run a new copy in parallel. And will kill the others if one of them complete.
This JIRA is an umbrella to apply this kind of idea in FLINK. Details will be append later.
1.
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Distinguish long tail task based on IOMetrics |
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Open | Unassigned |
2.
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Speculatively schedule execution for long tail task |
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Open | Unassigned |
