[Question] [java client] CPU-intensive code on io threads

[Andrey Yegorov]

Hi,

While looking through the code/thread dumps I noticed that decompression of
compressed payload happens on pulsar-client-io threads
Specifically:
https://github.com/apache/pulsar/blob/80c5791b87482bee3392308ecef45f455f8de885/pulsar-client/src/main/java/org/apache/pulsar/client/impl/ClientCnx.java#L495-L505
handleMessage runs on the pulsar-client-io thread (used by netty)
and consumer.messageReceived() will do decompression of the payload on
the netty thread, which is a bad practice in my understanding.

I am not very familiar with client's thread pools, are there any reasons
not to movemessageReceived() to internalPinnedExecutor, like

consumer.internalPinnedExecutor.submit(() -> {
     consumer.messageReceived(cmdMessage, headersAndPayload,
ClientCnx.this);
 });

--
Andrey