[jira] [Created] (KAFKA-4293) ByteBufferMessageSet.deepIterator burns CPU catching EOFExceptions

["radai rosenblatt (JIRA)" <ji...@apache.org>]

radai rosenblatt created KAFKA-4293:
---------------------------------------

             Summary: ByteBufferMessageSet.deepIterator burns CPU catching EOFExceptions
                 Key: KAFKA-4293
                 URL: https://issues.apache.org/jira/browse/KAFKA-4293
             Project: Kafka
          Issue Type: Bug
          Components: core
    Affects Versions: 0.10.0.1
            Reporter: radai rosenblatt


around line 110:
{noformat}
try {
    while (true)
        innerMessageAndOffsets.add(readMessageFromStream(compressed))
} catch {
    case eofe: EOFException =>
    // we don't do anything at all here, because the finally
    // will close the compressed input stream, and we simply
    // want to return the innerMessageAndOffsets
{noformat}

the only indication the code has that the end of the oteration was reached is by catching EOFException (which will be thrown inside readMessageFromStream()).

profiling runs performed at linkedIn show 10% of the total broker CPU time taken up by Throwable.fillInStack() because of this behaviour.

unfortunately InputStream.available() cannot be relied upon (concrete example - GZipInputStream will not correctly return 0) so the fix would probably be a wire format change to also encode the number of messages.



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