[SPARK-21225] decrease the Mem using for variable 'tasks' in function resourceOffers

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.1.0, 2.1.1
• Fix Version/s: 2.3.0
• Component/s: Spark Core
• Assignee: yangZhiguo
• Reporter: yangZhiguo
• Created: 27/Jun/17 09:29
• Updated: 29/Jun/17 12:56
• Resolved: 29/Jun/17 12:54

Description

In the function 'resourceOffers', It declare a variable 'tasks' for storage the tasks which have allocated a executor. It declared like this:
val tasks = shuffledOffers.map(o => new ArrayBuffer[TaskDescription](o.cores))

But, I think this code only conside a situation for that one task per core. If the user config the "spark.task.cpus" as 2 or 3, It really don't need so much space. I think It can motify as follow:

val tasks = shuffledOffers.map(o => new ArrayBuffer[TaskDescription](Math.ceil(o.cores*1.0/CPUS_PER_TASK).toInt))

Issue Links

• links to: [Github] Pull Request #18434 (JackYangzg)
• links to: [Github] Pull Request #18435 (JackYangzg)