James, this explanation was quite clear and interesting. Never used provisioned concurrency but now that I know what it actually does, I might start using it. I have always been a little unclear how reserved concurrency works when a lambda is set as a trigger for draining an SQS queue. If I have set it to 1 does just one item get picked up from the queue to process or do items get picked up and if there is already one being processed, it gets thrown back to the queue and then is picked up after the configured visibility timeout? Would you have some insight on this?
Fantastic question! So reserved concurrency restricts the number of Lambda execution environments. However, it does not change the behaviour of the SQS pollers. So if you had 100 messages in the queue and your reserved concurrency to 1, Lambda would still try to send all 100 to your function. Clearly, the majority of these would fail and be returned to the queue. So on and so forth... The best way to control the behaviour of how messages are pulled off SQS is using the settings on the event source itself (Batching window, batch size) as opposed to reserved concurrency.
Indeed! I had some feedback on the video and am going to revamp it slightly. The Lambda fundamentals content is very much on my radar still, it's just been rehashed slightly ☺️
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This was helpful. Thanks!
James, this explanation was quite clear and interesting. Never used provisioned concurrency but now that I know what it actually does, I might start using it. I have always been a little unclear how reserved concurrency works when a lambda is set as a trigger for draining an SQS queue. If I have set it to 1 does just one item get picked up from the queue to process or do items get picked up and if there is already one being processed, it gets thrown back to the queue and then is picked up after the configured visibility timeout? Would you have some insight on this?
Fantastic question! So reserved concurrency restricts the number of Lambda execution environments. However, it does not change the behaviour of the SQS pollers. So if you had 100 messages in the queue and your reserved concurrency to 1, Lambda would still try to send all 100 to your function. Clearly, the majority of these would fail and be returned to the queue. So on and so forth...
The best way to control the behaviour of how messages are pulled off SQS is using the settings on the event source itself (Batching window, batch size) as opposed to reserved concurrency.
@@serverlessjames Thanks for your response. Going to subscribe to your channel
@@paragnairdev thanks, I appreciate you subscribing 🫂
why did you remove your video about lambda request processing 🤔. I marked it to watch it later now I see its removed :(
Indeed! I had some feedback on the video and am going to revamp it slightly. The Lambda fundamentals content is very much on my radar still, it's just been rehashed slightly ☺️