enable.auto.commit semantics

[Peter Levart]

Hello,

I'm using Java KafkaConsumer and I'm wondering what is the guarantee of 
consuming messages when enable.auto.commit is set to true.

What is the earliest time the offsets of messages returned from last 
poll() may be committed? Immediately after returning from poll() or upon 
next call to poll()?

If it is the former, am I right to assume that messages may get lost in 
the event of consumer crash?

If that is the case then the only way to guarantee that no message will 
get lost is to commit consumed offsets manually after processing the 
messages returned from poll(), right?

Thanks, Peter