What is “speculative execution” in Hadoop?

Question

What is the meaning of 'speculative execution' in Hadoop?

Answer 1

In Hadoop, the term "speculative execution" is used when a node is assigned a task and the node appears to be executing the task slower than expected, in which case, the master node assigns another instance of the same task to another executor node. Now, whichever node executes the task first, the output is taken from that node and the concurrent task being executed on the pending node is terminated or killed.

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