THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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When speculative execution is enabled, a SpeculativeScheduler(which extends AdaptiveBatchScheduler) will be used for task scheduling. SpeculativeScheduler will listen on slow tasks detected by SlowTaskDetector. It will create and deploy speculative executions for the slow tasks. Nodes that slow tasks located on will be treated as slow nodes and get blacklisted, so that speculative executions will not be deployed on them.
SlowTaskDetector
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