otterc commented on a change in pull request #30433:
URL: https://github.com/apache/spark/pull/30433#discussion_r529823126



##########
File path: 
common/network-shuffle/src/main/java/org/apache/spark/network/shuffle/RemoteBlockPushResolver.java
##########
@@ -827,13 +833,16 @@ void resetChunkTracker() {
     void updateChunkInfo(long chunkOffset, int mapIndex) throws IOException {
       long idxStartPos = -1;
       try {
-        // update the chunk tracker to meta file before index file
-        writeChunkTracker(mapIndex);
         idxStartPos = indexFile.getFilePointer();
         logger.trace("{} shuffleId {} reduceId {} updated index current {} 
updated {}",
           appShuffleId.appId, appShuffleId.shuffleId, reduceId, 
this.lastChunkOffset,
           chunkOffset);
-        indexFile.writeLong(chunkOffset);
+        indexFile.write(Longs.toByteArray(chunkOffset));
+        // Chunk bitmap should be written to the meta file after the index 
file because if there are
+        // any exceptions during writing the offset to the index file, meta 
file should not be
+        // updated. If the update to the index file is successful but the 
update to meta file isn't
+        // then the index file position is reset in the catch clause.
+        writeChunkTracker(mapIndex);

Review comment:
       Had a discussion with @Victsm @mridulm yesterday. This is the approach 
currently we are thinking of:
   1. Verify if `seek` is not recoverable. If it is not then let the clients 
know to stop pushing and stop merging this partition.
   2. Have a threshold on number of `IOExceptions` from writes and when this 
threshold is reached for a single partition, inform the client to stop pushing 
and stop merging this partition.
   3. When  the update to metadata fails, not propagate this exception back to 
client so that they push the block again. The size of the current chunk may 
grow but with (2) in place it will still be of a manageable size.
   
   These changes will not be that complex.
   




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