Major Description
In KAFKA-3135, users have reported a strange pause when consuming data using the new consumer. This can be easily reproduced with the console consumer, but the root cause has so far proven elusive. Interestingly, the pause can also be reproduced with the old consumer if you change the socket buffer size to 32K to match the new consumer's default. Similarly, by increasing the new consumer's connection receive buffer size to 64K to match the old consumer's default, the problem seems to be mitigated (I am unable to reproduce it locally with this setting, though others have reported that its impact is merely reduced). Since there doesn't appear to be a good reason to have lowered the default for the new consumer, we may as well revert to the old consumer's default of 64K and accept the mitigation until an actual fix is found.