squito commented on a change in pull request #23453: [SPARK-26089][CORE] Handle
corruption in large shuffle blocks
URL: https://github.com/apache/spark/pull/23453#discussion_r264273772
##########
File path:
core/src/main/scala/org/apache/spark/storage/ShuffleBlockFetcherIterator.scala
##########
@@ -466,16 +469,19 @@ final class ShuffleBlockFetcherIterator(
var isStreamCopied: Boolean = false
try {
input = streamWrapper(blockId, in)
- // Only copy the stream if it's wrapped by compression or
encryption, also the size of
- // block is small (the decompressed block is smaller than
maxBytesInFlight)
- if (detectCorrupt && !input.eq(in) && size < maxBytesInFlight / 3)
{
+ // Only copy the stream if it's wrapped by compression or
encryption upto a size of
+ // maxBytesInFlight/3. If stream is longer, then corruption will
be caught while reading
+ // the stream.
+ streamCompressedOrEncrypted = !input.eq(in)
+ if (streamCompressedOrEncrypted && detectCorruptUseExtraMemory) {
isStreamCopied = true
- val out = new ChunkedByteBufferOutputStream(64 * 1024,
ByteBuffer.allocate)
- // Decompress the whole block at once to detect any corruption,
which could increase
- // the memory usage tne potential increase the chance of OOM.
+ // Decompress the block upto maxBytesInFlight/3 at once to
detect any corruption which
+ // could increase the memory usage and potentially increase the
chance of OOM.
Review comment:
this comment & the one just above the `if` are redundant and a little bit
wrong -- I think you only need one comment (don't care whether its above or
below the if) and should be something more like:
We optionally decompress the first maxBytesInFlight/3 bytes into memory, to
check for corruption in that portion of the data. But even if that
configuration is off, or if the corruption is later, we'll still try to detect
the corruption later in the stream.
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