4 ms·

PC doesn't make that much sense for a use case like mine, where absolute cost minimization is the goal. My request volume (including ping requests) easily fits

PC doesn't make that much sense for a use case like mine, where absolute cost minimization is the goal. My request volume (including ping requests) easily fits into the Lambda free tier, whereas with PC I'd be looking at some cost. More generally, I feel PC kinda defeats the purpose of Lambda to begin with. If I'm in that range of continuous load, I'd rather look at more traditional means of provisioning and hosting this application.

websap 5y ago
PC is a good way to keep certain amount of performance guarantees. It seems like you’re solution fits into the free tier, so probably a bad idea for you.
zxcvbn4038 5y ago
I think you are thinking of reserved concurrency - with reserved concurrency you can only run as many instances as you have reserved. With provisioned concurrency you can run as many as your quota allows but you are guaranteed to be able to handle as many concurrent instances have provisioned. Neither one of these are going to help you with cold start times, it is not defining the number of instances running, its just reserving a portion of quota so that they can run. Where provisioned/reserved concurrency comes in useful is keeping a run-away lambda function from starving out other functions either by guaranteeing a portion of the quota for the other functions or keeping a function from exceeding a number of concurrent executions. The "ping" technique you mentioned is one way to keep a function warm but if lambda decides to start a second instance of the function because the hot one is handling a request, then that person is going to take a warm up hit and nothing you can do about that. If you are really latency sensitive then lambda might not be the right choice for you. You can get a t4g.nano SPOT instance for about $3.50/month and you can keep that warm, but that is probably a whole lot more then you are paying for lambda.
- gjhr 5y ago
  Provisioned concurreny does decrease cold starts. Reserved concurrency both guarantees a portion of your concurrency limit be allocated to a lambda as well as capping concurrency of that lambda to that portion. Reserved concurrency has no cost associated. Provisioned concurrency keeps a certain number of execution environments warm for your use. Provisioned concurrency costs money.
  - itisit 5y ago
    > Provisioned concurreny does decrease cold starts. Indeed it does. https://aws.amazon.com/blogs/aws/new-provisioned-concurrency-for-lambda-functions/ https://aws.amazon.com/blogs/aws/new-provisioned-concurrency... https://docs.aws.amazon.com/lambda/latest/dg/provisioned-concurrency.html https://docs.aws.amazon.com/lambda/latest/dg/provisioned-con...

websap 5y ago

PC is a good way to keep certain amount of performance guarantees. It seems like you’re solution fits into the free tier, so probably a bad idea for you.

zxcvbn4038 5y ago

I think you are thinking of reserved concurrency - with reserved concurrency you can only run as many instances as you have reserved. With provisioned concurrency you can run as many as your quota allows but you are guaranteed to be able to handle as many concurrent instances have provisioned. Neither one of these are going to help you with cold start times, it is not defining the number of instances running, its just reserving a portion of quota so that they can run. Where provisioned/reserved concurrency comes in useful is keeping a run-away lambda function from starving out other functions either by guaranteeing a portion of the quota for the other functions or keeping a function from exceeding a number of concurrent executions. The "ping" technique you mentioned is one way to keep a function warm but if lambda decides to start a second instance of the function because the hot one is handling a request, then that person is going to take a warm up hit and nothing you can do about that. If you are really latency sensitive then lambda might not be the right choice for you. You can get a t4g.nano SPOT instance for about $3.50/month and you can keep that warm, but that is probably a whole lot more then you are paying for lambda.

gjhr 5y ago
Provisioned concurreny does decrease cold starts. Reserved concurrency both guarantees a portion of your concurrency limit be allocated to a lambda as well as capping concurrency of that lambda to that portion. Reserved concurrency has no cost associated. Provisioned concurrency keeps a certain number of execution environments warm for your use. Provisioned concurrency costs money.
- itisit 5y ago
  > Provisioned concurreny does decrease cold starts. Indeed it does. https://aws.amazon.com/blogs/aws/new-provisioned-concurrency-for-lambda-functions/ https://aws.amazon.com/blogs/aws/new-provisioned-concurrency... https://docs.aws.amazon.com/lambda/latest/dg/provisioned-concurrency.html https://docs.aws.amazon.com/lambda/latest/dg/provisioned-con...