Thanks Roshan for the detailed answer. This is for a research project, which assumes a topology configured in an at most once semantics. Loss of tuples is tolerable. We want to study the relationship between maximum throughput and the amount of processing power (mainly CPU) allocated to the topology. We want to ensure that the topology is using as much of the CPU provided to it. In case of backpressure, the input it getting throttled. (I am additionally using cgroups to control the amount of CPU allocated to each component. So storm 2.0 is my only option).
Is it possible to configure storm to simulate at most once semantics, where the topology is not throttled by back pressure? Thanks again for your time, Warm regards, ravi ________________________________ From: Roshan Naik <roshan_n...@yahoo.com> Sent: Thursday, April 12, 2018 1:09 PM To: email@example.com Subject: Re: Disable backpressure in Storm 2.0 Short answer: It is not possible to disable backpressure in 2.0 and you don't want to do it either. Long Answer: That setting applies to the 1.0 backpressure subsystem (zookeeper based) which is layered on top of the messaging system. Storm 2.0 has a new messaging subsystem and a very lightweight backpressure model that is tightly integrated into the messaging subsystem (with no ZK or other external dependencies). WRT why you don't want to disable it... If you disable backpressure & allow upstream components to blindly pump out messages, then you are left with two options to handle a BP situation. To hold the excess messages, you could allow the internal queues to keep growing in an unbounded fashion, in which case the worker process will die with an OOM exception relatively quickly. The other option is to keep the queues bounded and drop messages once queues are full. Both options are bad options. In Storm 1.x you could disable the BP system (default) and fallback on topology.max.spout.pending as an alternative BP model (if acking is enabled). If ACKing was disabled and BP is also disabled it is easy to crash the workers. Any reason you are looking to disable BP ? -roshan On Wednesday, April 11, 2018, 7:42:29 PM PDT, ravi kiran puttaswamy <ravikiran.m...@live.com> wrote: Hello all, I am configuring a storm topology to execute in at-most once semantics without backpressure. Can you let me know how to disable backpressure in storm 2.0? The documentation says the earlier config "topology.backpressue.enable" will be deprecated and removed from storm 2.0. thanks and regards, ravi