Github user davies commented on a diff in the pull request:
https://github.com/apache/spark/pull/15923#discussion_r93671999
--- 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 --
@fathersson The checksum in TCP is only 16 bits, it's not strong enough
for large traffic, usually DFS or other system with heavy TCP traffic will have
another application level checksum. Adding to @rxin 's point, we did see this
retry helped in production to work around temporary corrupt.
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