Github user gatorsmile commented on a diff in the pull request:
https://github.com/apache/spark/pull/21638#discussion_r215030825
--- Diff:
core/src/main/scala/org/apache/spark/input/PortableDataStream.scala ---
@@ -47,7 +47,7 @@ private[spark] abstract class StreamFileInputFormat[T]
def setMinPartitions(sc: SparkContext, context: JobContext,
minPartitions: Int) {
val defaultMaxSplitBytes =
sc.getConf.get(config.FILES_MAX_PARTITION_BYTES)
val openCostInBytes = sc.getConf.get(config.FILES_OPEN_COST_IN_BYTES)
- val defaultParallelism = sc.defaultParallelism
+ val defaultParallelism = Math.max(sc.defaultParallelism, minPartitions)
--- End diff --
```
sc = new SparkContext(new
SparkConf().setAppName("test").setMaster("local")
.set(config.FILES_OPEN_COST_IN_BYTES.key, "0")
.set("spark.default.parallelism", "1"))
println(sc.binaryFiles(dirpath1, minPartitions = 50).getNumPartitions)
println(sc.binaryFiles(dirpath1, minPartitions = 1).getNumPartitions)
```
It is not hard to verify whether the parameter `minPartitions` takes an
effect. Currently, the description of this parameter is not clear. We need to
document it clear which factors impact the actual number of partitions;
otherwise, users will not understand how to use it.
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