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  1. Spark
  2. SPARK-21923

Avoid calling reserveUnrollMemoryForThisTask for every record

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    Details

    • Type: Improvement
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 2.2.0
    • Fix Version/s: 2.3.0
    • Component/s: Spark Core
    • Labels:
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      Description

      When Spark persist data to Unsafe memory, we call the method `MemoryStore.putIteratorAsBytes`, which need synchronize the `memoryManager` for every record write. This implementation is not necessary, we can apply for more memory at a time to reduce unnecessary synchronization.

      Test case:
      ```scala
      val start = System.currentTimeMillis()
      val data = sc.parallelize(0 until Integer.MAX_VALUE, 100)
      .persist(StorageLevel.OFF_HEAP)
      .count()

      println(System.currentTimeMillis() - start)

      ```

      Test result:

      before

      27647 29108 28591 28264 27232

      after

      26868 26358 27767 26653 26693

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            • Assignee:
              coneyliu Xianyang Liu
              Reporter:
              coneyliu Xianyang Liu
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              Dates

              • Created:
                Updated:
                Resolved: