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From Arthur Li <>
Subject Question about relationship between number of files and initial tasks(partitions)
Date Thu, 04 Apr 2019 01:37:08 GMT
Hi Sparkers,

I noticed that in my spark application, the number of tasks in the first
stage is equal to the number of files read by the application(at least for
Avro) if the number of cpu cores is less than the number of files. Though
If cpu cores are more than number of files, it's usually equal to default
parallelism number. Why is it behave like this? Would this require a lot of
resource from the driver? Is there any way we can do to decrease the number
of tasks(partitions) in the first stage without merge files before loading?


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