Thread by @forrestbrazeal

Lambda Provisioned Concurrency is here! I had a chance to experiment with the feature before release, and while there's no beating @theburningmonk's thorough review, I do have a few thoughts and caveats. 1/

lumigo.io/blog/the-end-o…

@theburningmonk First, know that this does not change the fundamental behavior of Lambda. You are NOT getting long-lived, stateful, provisioned instances. AWS will still recycle the underlying execution environments every few hours. (Don't complain, you want this.) 2/

@theburningmonk This means that provisioned-concurrent functions can and will lose cached state! While the provisioned instance will load init code outside your handler, it obviously won't preserve any updates to that global state made by invocations. Adjust your assumptions accordingly. 3/

@theburningmonk Now, a lot of us have done our best to put cold start in perspective, saying it's not that big a deal with the proper languages and config. Well, if you're running legacy Java and .NET, it's a very big deal. This feature is HUGE for enterprises. 4/

@theburningmonk I'm really excited about the doors this opens for enterprise devs now. Instead of dismissing Lambda as a non-starter due to 30-second cold starts (seen it), we can flip a switch and change the conversation. 5/

@theburningmonk Should provisioned concurrency be your default for new apps? In my opinion, no. Lot of places where cold start doesn't matter or can reach an acceptable minimum. But for legacy stuff? Heck yes, inject that sweet provisioned concurrency into my veins. 6/

@theburningmonk TL;DR -- Lambda just became impossible to ignore in enterprise architecture discussions. Provisioned concurrency is a small compromise with Lambda's vision, but a quantum leap forward for adoption. /end