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https://issues.apache.org/jira/browse/KAFKA-4852?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Matthias J. Sax reopened KAFKA-4852:
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Assignee: (was: LinShunkang)
> ByteBufferSerializer not compatible with offsets
> ------------------------------------------------
>
> Key: KAFKA-4852
> URL: https://issues.apache.org/jira/browse/KAFKA-4852
> Project: Kafka
> Issue Type: Bug
> Components: clients
> Affects Versions: 0.10.1.1
> Environment: all
> Reporter: Werner Daehn
> Priority: Minor
> Fix For: 3.4.0
>
>
> Quick intro: A ByteBuffer.rewind() resets the position to zero. What if the
> ByteBuffer was created with an offset? new ByteBuffer(data, 3, 10)? The
> ByteBufferSerializer will send from pos=0 and not from pos=3 onwards.
> Solution: No rewind() but flip() for reading a ByteBuffer. That's what the
> flip is meant for.
> Story:
> Imagine the incoming data comes from a byte[], e.g. a network stream
> containing topicname, partition, key, value, ... and you want to create a new
> ProducerRecord for that. As the constructor of ProducerRecord requires
> (topic, partition, key, value) you have to copy from above byte[] the key and
> value. That means there is a memcopy taking place. Since the payload can be
> potentially large, that introduces a lot of overhead. Twice the memory.
> A nice solution to this problem is to simply wrap the network byte[] into new
> ByteBuffers:
> ByteBuffer key = ByteBuffer.wrap(data, keystart, keylength);
> ByteBuffer value = ByteBuffer.wrap(data, valuestart, valuelength);
> and then use the ByteBufferSerializer instead of the ByteArraySerializer.
> But that does not work as the ByteBufferSerializer does a rewind(), hence
> both, key and value, will start at position=0 of the data[].
> public class ByteBufferSerializer implements Serializer<ByteBuffer> {
> public byte[] serialize(String topic, ByteBuffer data) {
> data.rewind();
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