Details
-
Improvement
-
Status: Resolved
-
Major
-
Resolution: Fixed
-
2.2.0
-
None
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 |
