Ngone51 commented on a change in pull request #31495:
URL: https://github.com/apache/spark/pull/31495#discussion_r571434693
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/HDFSMetadataLog.scala
##########
@@ -239,18 +239,35 @@ class HDFSMetadataLog[T <: AnyRef :
ClassTag](sparkSession: SparkSession, path:
.reverse
}
+ private var lastPurgedBatchId: Long = -1L
+
/**
* Removes all the log entry earlier than thresholdBatchId (exclusive).
*/
override def purge(thresholdBatchId: Long): Unit = {
- val batchIds = fileManager.list(metadataPath, batchFilesFilter)
- .map(f => pathToBatchId(f.getPath))
-
- for (batchId <- batchIds if batchId < thresholdBatchId) {
- val path = batchIdToPath(batchId)
- fileManager.delete(path)
- logTrace(s"Removed metadata log file: $path")
+ val possibleTargetBatchIds = (lastPurgedBatchId + 1 until thresholdBatchId)
+ if (possibleTargetBatchIds.length <= 3) {
Review comment:
Usually, `possibleTargetBatchIds.length` should be 1?
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/HDFSMetadataLog.scala
##########
@@ -239,18 +239,35 @@ class HDFSMetadataLog[T <: AnyRef :
ClassTag](sparkSession: SparkSession, path:
.reverse
}
+ private var lastPurgedBatchId: Long = -1L
+
/**
* Removes all the log entry earlier than thresholdBatchId (exclusive).
*/
override def purge(thresholdBatchId: Long): Unit = {
- val batchIds = fileManager.list(metadataPath, batchFilesFilter)
- .map(f => pathToBatchId(f.getPath))
-
- for (batchId <- batchIds if batchId < thresholdBatchId) {
- val path = batchIdToPath(batchId)
- fileManager.delete(path)
- logTrace(s"Removed metadata log file: $path")
+ val possibleTargetBatchIds = (lastPurgedBatchId + 1 until thresholdBatchId)
+ if (possibleTargetBatchIds.length <= 3) {
+ // avoid using list if we only need to purge at most 3 elements
+ possibleTargetBatchIds.foreach { batchId =>
+ val path = batchIdToPath(batchId)
+ if (fileManager.exists(path)) {
Review comment:
This confused me. Why not blindly delete the path as the original way
does?
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/OffsetSeqLog.scala
##########
@@ -46,6 +47,23 @@ import org.apache.spark.sql.connector.read.streaming.{Offset
=> OffsetV2}
class OffsetSeqLog(sparkSession: SparkSession, path: String)
extends HDFSMetadataLog[OffsetSeq](sparkSession, path) {
+ private val cachedMetadata = new ju.TreeMap[Long, OffsetSeq]()
+
+ override def add(batchId: Long, metadata: OffsetSeq): Boolean = {
+ val added = super.add(batchId, metadata)
+ if (added) {
+ // cache metadata as it will be read again
+ cachedMetadata.put(batchId, metadata)
+ // we don't access metadata for (batchId - 2) batches; evict them
Review comment:
`TreeMap` seems overkill to me if we only cache at most 2 batches. How
about using a 2-size array? We can put/get the elements by the index of
(batchId % 2).
For example:
```scala
private val cachedMetadata = Array[OffsetSeq](null, null)
// put
cachedMetadata(batchId % 2) = metadata
// get
Option(cachedMetadata.get(batchId % 2)).orElse(super.get(batchId))
```
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