GitHub user witgo opened a pull request:
https://github.com/apache/spark/pull/17329
[SPARK-19991]FileSegmentManagedBuffer performance improvement
FileSegmentManagedBuffer performance improvement.
## What changes were proposed in this pull request?
When we do not set the value of the configuration items
`spark.storage.memoryMapThreshold` and `spark.shuffle.io.lazyFD`,
each call to the cFileSegmentManagedBuffer.nioByteBuffer or
FileSegmentManagedBuffer.createInputStream method creates a
NoSuchElementException instance. This is a more time-consuming operation.
In the use case, this PR can improve the performance of about 3.5%
The test code:
``` scala
(1 to 10).foreach { i =>
val numPartition = 10000
val rdd = sc.parallelize(0 until
numPartition).repartition(numPartition).flatMap { t =>
(0 until numPartition).map(r => r * numPartition + t)
}.repartition(numPartition)
val serializeStart = System.currentTimeMillis()
rdd.sum()
val serializeFinish = System.currentTimeMillis()
println(f"Test $i: ${(serializeFinish - serializeStart) / 1000D}%1.2f")
}
```
and `spark-defaults.conf` file:
```
spark.master yarn-client
spark.executor.instances 20
spark.driver.memory 64g
spark.executor.memory 30g
spark.executor.cores 5
spark.default.parallelism 100
spark.sql.shuffle.partitions 100
spark.serializer
org.apache.spark.serializer.KryoSerializer
spark.driver.maxResultSize 0
spark.ui.enabled false
spark.driver.extraJavaOptions -XX:+UseG1GC
-XX:+UseStringDeduplication -XX:G1HeapRegionSize=16M -XX:MetaspaceSize=512M
spark.executor.extraJavaOptions -XX:+UseG1GC
-XX:+UseStringDeduplication -XX:G1HeapRegionSize=16M -XX:MetaspaceSize=256M
spark.cleaner.referenceTracking.blocking true
spark.cleaner.referenceTracking.blocking.shuffle true
```
The test results are as follows
| [SPARK-19991](https://github.com/witgo/spark/tree/SPARK-19991)
|https://github.com/apache/spark/commit/68ea290b3aa89b2a539d13ea2c18bdb5a651b2bf|
|---| --- |
|226.09 s| 235.21 s|
## How was this patch tested?
Existing tests.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/witgo/spark SPARK-19991
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/17329.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #17329
----
commit abcfc79991ecd1d5cef2cd1e275b872695ba19d9
Author: Guoqiang Li <liguoqia...@huawei.com>
Date: 2017-03-17T03:19:37Z
FileSegmentManagedBuffer performance improvement
----
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