Hi Luke, Nice suggestion. It should optimize how memory is used with different production rates, but I wonder if we can take this idea further and improve batching in general.
Currently batch.size is used in two conditions: 1. When we append records to a batch in the accumulator, we create a new batch if the current batch would exceed the batch.size. 2. When we drain the batch from the accumulator, a batch becomes 'ready' when it reaches batch.size. The second condition is good with the current batch size, because if linger.ms is greater than 0, the send can be triggered by accomplishing the batching goal. The first condition, though, leads to creating many batches if the network latency or production rate (or both) is high, and with 5 in-flight and 16KB batches we can only have 80KB of data in-flight per partition. Which means that with 50ms latency, we can only push ~1.6MB/sec per partition (this goes down if we consider higher latencies, e.g. with 100ms we can only push ~0.8MB/sec). I think it would be great to separate the two sizes: 1. When appending records to a batch, create a new batch if the current exceeds a larger size (we can call it batch.max.size), say 256KB by default. 2. When we drain, consider batch 'ready' if it exceeds batch.size, which is 16KB by default. For memory conservation we may introduce batch.initial.size if we want to have a flexibility to make it even smaller than batch.size, or we can just always use batch.size as the initial size (in which case we don't need batch.initial.size config). -Artem On Fri, Oct 22, 2021 at 1:52 AM Luke Chen <show...@gmail.com> wrote: > Hi Kafka dev, > I'd like to start a vote for the proposal: KIP-782: Expandable batch size > in producer. > > The main purpose for this KIP is to have better memory usage in producer, > and also save users from the dilemma while setting the batch size > configuration. After this KIP, users can set a higher batch.size without > worries, and of course, with an appropriate "batch.initial.size". > > Derailed description can be found here: > > https://cwiki.apache.org/confluence/display/KAFKA/KIP-782%3A+Expandable+batch+size+in+producer > > Any comments and feedback are welcome. > > Thank you. > Luke >
