Github user Tagar commented on a diff in the pull request:
https://github.com/apache/spark/pull/15923#discussion_r94356127
--- Diff:
core/src/main/scala/org/apache/spark/storage/ShuffleBlockFetcherIterator.scala
---
@@ -305,40 +316,84 @@ final class ShuffleBlockFetcherIterator(
*/
override def next(): (BlockId, InputStream) = {
numBlocksProcessed += 1
- val startFetchWait = System.currentTimeMillis()
- currentResult = results.take()
- val result = currentResult
- val stopFetchWait = System.currentTimeMillis()
- shuffleMetrics.incFetchWaitTime(stopFetchWait - startFetchWait)
-
- result match {
- case SuccessFetchResult(_, address, size, buf, isNetworkReqDone) =>
- if (address != blockManager.blockManagerId) {
- shuffleMetrics.incRemoteBytesRead(buf.size)
- shuffleMetrics.incRemoteBlocksFetched(1)
- }
- bytesInFlight -= size
- if (isNetworkReqDone) {
- reqsInFlight -= 1
- logDebug("Number of requests in flight " + reqsInFlight)
- }
- case _ =>
- }
- // Send fetch requests up to maxBytesInFlight
- fetchUpToMaxBytes()
- result match {
- case FailureFetchResult(blockId, address, e) =>
- throwFetchFailedException(blockId, address, e)
+ var result: FetchResult = null
+ var input: InputStream = null
+ // Take the next fetched result and try to decompress it to detect
data corruption,
+ // then fetch it one more time if it's corrupt, throw
FailureFetchResult if the second fetch
--- End diff --
Is netty/shuffle data being compressed using Snappy algorithm by default?
If so, might be good to idea to enable checksum checking at Netty level too?
https://netty.io/4.0/api/io/netty/handler/codec/compression/SnappyFramedDecoder.html
> Note that by default, validation of the checksum header in each chunk is
DISABLED for performance improvements. If performance is less of an issue, or
if you would prefer the safety that checksum validation brings, please use the
SnappyFramedDecoder(boolean) constructor with the argument set to true.
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