There is no way to reserve Lambda concurrency without reducing the unreserved concurrency, but the unreserved concurrency can be easily increased with a support request, which you can open directly from the Service Quotas page: https://us-east-1.console.aws.amazon.com/servicequotas/home/services/lambda/quotas/L-B99A9384
Answer from Shahar Mosek on Stack OverflowAmazon Web Services
docs.aws.amazon.com › aws lambda › developer guide › understanding lambda function scaling › configuring reserved concurrency for a function
Configuring reserved concurrency for a function - AWS Lambda
In Lambda, concurrency is the number of in-flight requests that your function is currently handling. There are two types of concurrency controls available: Reserved concurrency – This sets both the maximum and minimum number of concurrent instances allocated to your function.
Amazon Web Services
docs.aws.amazon.com › aws lambda › developer guide › understanding lambda function scaling
Understanding Lambda function scaling - AWS Lambda
By default, Lambda provides your account with a total concurrency limit of 1,000 concurrent executions across all functions in an AWS Region. To support your specific account needs, you can request a quota increase · and configure function-level concurrency controls so that your critical functions ...
amazon web services - AWS Lambda limit concurrency from Unreserved concurrency pool - Stack Overflow
If you are worried about consuming concurrency, you can always ask AWS for an increase to the default limit of 1000 concurrent executions. ... Obviously not, no. ... There is no way to reserve Lambda concurrency without reducing the unreserved concurrency, but the unreserved concurrency can ... More on stackoverflow.com
How does Lambda reserved concurrency interact with Cloudwatch Events?
When your reserved concurrency is hit for a function, Lambda will respond to the client calling it’s Invoke API with a 429 status code. What happens next depends on the event source and it’s retry behavior. See here: https://docs.aws.amazon.com/lambda/latest/dg/invocation-retries.html More on reddit.com
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February 9, 2021AWS Lambda Reserved Concurrency
no, it is not possible. lambda instances don't know about each other. it has to be something about sqs visibility timeout, and some error in signaling the processing of messages. More on reddit.com
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December 27, 2024Better understanding in Lambda concurrency and power
By default you have a concurrency limit of 1000 across all lambdas in a region, per account. https://docs.aws.amazon.com/lambda/latest/dg/lambda-concurrency.html# This isn’t a hard quota, you can ask to increase it. As for your use case, seems that it matches what you have seen so far on your metrics. Just curious, Is there any reason why you set a reserved concurrency of 2000 for lambdas that are consuming an sqs queue ? More on reddit.com
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Reddit
reddit.com › r/aws › aws lambda reserved concurrency
r/aws on Reddit: AWS Lambda Reserved Concurrency
December 27, 2024 -
Hey! Maybe this is a dumb question, maybe a coincidence.
We have a lambda configured to use Reserved Concurrency = 5.
Sometimes this lambda takes more than a minute run and, when we trigger this lambda with more than 50 requests ( it is fired by sqs ), we notice that the lambda returns 5 by 5 and it ends its execution all 5 together.
For example, we have a bunch of requests which takes 5 seconds to process each, if we trigger our lambda with 40 requests if one take more than 30s, the lambda return 5 of the results together after 30 seconds, even if the others takes less than 2 or 3s.
Is this a common behavior for lambdas with reserved concurrency?
It sends 5 requests, waits until all 5 executes then send more 5? Or it send 5 requests, when one ends it sends another one to keep 5 itens running concurrently?
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no, it is not possible. lambda instances don't know about each other. it has to be something about sqs visibility timeout, and some error in signaling the processing of messages.
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Reserved Concurrency is to take from the account max lambda concurrency and allocate it to that function (version). The default account limit is 1000 concurrent lambda executions. This means 995 are still available for this or other functions. It is not a limit, just an allocation. Using SQS, the Lambda service starts with 5 workers. Each worker will pull up to your batch size of messages. The lambda function will process the entire batch within the timeout. It is recommended you have your lambda execution timeout set long enough to process the entire batch of messages. If any message in the batch fails, the entire batch will fail. So plan for idempotency - and best practice is for lambda function to delete each completed message from SQS upon completion, they way they won’t be returned as a failed message if the batch fails. Lambda service will add and remove workers based upon the size of SQS, oldest message and error rates. You have no control over this, other than by setting a maximum currency on your lambda function. So, your visibility time out on SQS needs to be long enough that the queue doesn’t just redrive the messages. Your lambda function needs to have execution time long enough to process the entire batch. You can adjust the batch size.
Lumigo
lumigo.io › guides › aws lambda performance optimization › aws lambda concurrency
AWS Lambda Concurrency - Lumigo
August 21, 2024 - Open the Lambda function, navigate to Functions page, and select a function. Select Configuration > Concurrency > Edit. Select the Reserve concurrency option and type a value. This value indicates the number of concurrent requests your function ...
Stack Overflow
stackoverflow.com › beta › discussions › 78231813 › difference-between-aws-lambda-reserved-and-unreserved-concurrency
Difference between AWS Lambda Reserved and Unreserved Concurrency - Stack Overflow
March 27, 2024 - Once the container is up, and the lambda is executed successfully, AWS keeps this container up to avoid cold start and waits for the next request from same function. From my experience this wait time is around 10 mins(not documented anywhere). 2. Now coming to Concurrency, the default limit is 1000(which can be increased upon requesting AWS).
AWS
aws.amazon.com › blogs › apn › implementing-serverless-tiering-strategies-with-aws-lambda-reserved-concurrency
Implementing Serverless Tiering Strategies with AWS Lambda Reserved Concurrency | AWS Partner Network (APN) Blog
August 29, 2023 - If the function is invoked again while the first Lambda function still runs, another instance is allocated, which increases the function’s concurrency. You can find more details on Lambda function scaling in the documentation. Continuing with the e-commerce example, if you are expecting 1,000 orders to be processed at the same time, 1,000 instances of your order processing function will be instantiated. All of your account’s functions in the same AWS Region without reserved concurrency share the pool of unreserved concurrency.
Sedai
sedai.io › blog › under-standing-aws-lambda-concurrency
AWS Lambda Concurrency Explained: Setup & Optimization | Sedai
Reserved concurrency in Lambda is a powerful tool that ensures a specific Lambda function always has the necessary concurrent execution slots available. This setup is crucial for high-priority functions, especially during peak loads, as it ...
Amazon Web Services
docs.aws.amazon.com › aws lambda › developer guide › understanding lambda function scaling › configuring provisioned concurrency for a function
Configuring provisioned concurrency for a function - AWS Lambda
In Lambda, concurrency is the number of in-flight requests that your function is currently handling. There are two types of concurrency controls available: Reserved concurrency – This sets both the maximum and minimum number of concurrent instances allocated to your function.
Amazon Web Services
docs.aws.amazon.com › aws lambda › api reference › data types › concurrency
Concurrency - AWS Lambda
The number of concurrent executions that are reserved for this function. For more information, see Managing Lambda reserved concurrency. ... Valid Range: Minimum value of 0. ... For more information about using this API in one of the language-specific AWS SDKs, see the following:
ITNEXT
itnext.io › the-everything-guide-to-lambda-throttling-reserved-concurrency-and-execution-limits-d64f144129e5
The Everything Guide to Lambda Throttling, Reserved Concurrency, and Execution Limits | by Kerri Rapes | ITNEXT
August 24, 2019 - Reserved Concurrences can be set on any or all of the lambdas, in any combination. However, AWS reserves 100 executions to the common pool at all times.
Orum
orum.io › home › blog › what is reserved concurrency and why is it important?
What is Reserved Concurrency and Why is it Important? - Orum
September 8, 2022 - Stripe is a suite of APIs powering online payment processing and commerce solutions for internet businesses of all sizes. Accept payments and scale faster with AI.
AWS re:Post
repost.aws › knowledge-center › lambda-reserved-concurrency
Troubleshoot Lambda reserved concurrency issues | AWS re:Post
October 26, 2022 - 1. Confirm that you've configured reserved concurrency for your Lambda function. Check the setting using the Lambda console or by calling the GetFunction API. Note: A Lambda function configured to have zero reserved concurrency is throttled ...
Medium
rajaswalavalkar.medium.com › aws-lambda-reserved-concurrency-v-s-provisioned-concurrency-scaling-db8e93703b02
AWS Lambda Reserved Concurrency v/s Provisioned Concurrency Scaling | by Rajas Walavalkar | Medium
January 4, 2022 - Thus AWS provides you to configure ... controls available · Reserved concurrency — It guarantees the maximum number of concurrent instances for the function which can be invoked....
iCompaas Support
support.icompaas.com › support › solutions › articles › 62000218450-ensure-lambda-concurrency-limit-is-configured
Ensure Lambda Concurrency Limit is Configured : iCompaas Support
March 31, 2023 - The functions cannot scale out ... you can reserve concurrency to prevent your function from using all the available concurrency in the Region, or from overloading downstream resources....
KodeKloud Notes
notes.kodekloud.com › docs › AWS-Lambda › Advanced-Topics › Reserved-and-Unreserved-Concurrency
Reserved and Unreserved Concurrency - KodeKloud Notes
Managing concurrency in AWS Lambda ensures that high-priority functions always have the capacity they need. By default, your account’s unreserved concurrency sets a soft limit on total parallel executions. For mission-critical workloads, you can allocate reserved concurrency to specific functions.
Substack
urielbitton.substack.com › p › using-reserved-vs-unreserved-concurrency
Using Reserved Vs Unreserved Concurrency in AWS Lambda
June 26, 2025 - When a function uses unreserved concurrency it can use up as much as it needs from the pool of total concurrency and starve other functions. Reserved concurrency on the other hand guarantees your function always has a set number of concurrency.
Orchestra
getorchestra.io › guides › configuring-reserved-concurrency-in-aws-lambda
Configuring reserved concurrency in AWS lambda | Orchestra
September 9, 2024 - By default, Lambda can scale automatically, up to a soft limit (which varies by account and region). Reserved concurrency is a configuration setting that allows you to specify the maximum number of concurrent executions for a Lambda function.
DEV Community
dev.to › prajwalnayak › concurrency-and-autoscaling-in-aws-lambda-3319
Concurrency and Autoscaling in AWS Lambda - DEV Community
February 16, 2025 - Types of Concurrency Unreserved ... Lambda functions in the account. Reserved Concurrency Guarantees a fixed number of concurrent executions for a specific function....
Amazon Web Services
docs.aws.amazon.com › aws lambda › api reference › actions › getfunctionconcurrency
GetFunctionConcurrency - AWS Lambda
Returns details about the reserved concurrency configuration for a function. To set a concurrency limit for a function, use PutFunctionConcurrency. GET /2019-09-30/functions/FunctionName/concurrency HTTP/1.1 · The request uses the following URI parameters. ... The name or ARN of the Lambda function. Function name – my-function. Function ARN – arn:aws...