HeartSaVioR commented on a change in pull request #31495:
URL: https://github.com/apache/spark/pull/31495#discussion_r572473687
##########
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:
Looks like adding the check doesn't contribute noticeable latency;
before the change (exist -> delete)
```
grep "walCommit took" driver_stderr.log | awk '{print $7}' | head -n 1100 |
tail -n 1000 | datamash max 1 min 1 mean 1 median 1 perc:90 1 perc:95 1 perc:99
1
1874 152 242.131 220.5 306 342 654.84
```
after the change (delete)
```
grep "walCommit took" driver_stderr.log | awk '{print $7}' | head -n 1100 |
tail -n 1000 | datamash max 1 min 1 mean 1 median 1 perc:90 1 perc:95 1 perc:99
1
1882 156 252.162 231.5 311 357.2 559.16
```
but I agree the check is unnecessary. Will remove it.
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