title: What does it mean when AWS says lambda has limit for 1000 concurrent execution?
body: <p>I am trying to understand the limits of AWS lambda mentioned on the <a href="https://docs.aws.amazon.com/lambda/latest/dg/limits.html" rel="nofollow noreferrer">AWS Lambda Limits</a> documentation page.</p>
  
  <p>It says that Lambda has a limit of <strong>1000 concurrent executions</strong>. </p>
  
  <p>Let's say we have a Lambda <code>FunctionX</code>, It takes a <code>folderName</code> from an S3 bucket and processes each item in that folder. </p>
  
  <p>Now, I know that Lambda serves each request independently. So if 1000 users try to Invoke <code>FunctionX</code>, with different folder names, <code>FunctionX</code> will serve each request independently and process each folder. </p>
  
  <p>Does this mean if 1001 requests are made then the Lambda <code>FunctionX</code> will not process the additional 1 request? </p>
  
  <p>OR, </p>
  
  <p>By concurrency, does AWS mean, when <code>FunctionX</code> is executing for <code>user1</code>, it can process 1000 items in that folder concurrently. (Can create 1000 threads to process the items in the folder?)</p>
  
  <p>OR, </p>
  
  <p>I can have <em>N</em> different lambda functions, (F1, F2...., F1000, F1001, FN), handling different functionality. And at a time any 1000 unique Lambda functions can execute concurrently?</p>