Disconnect for Lambda?

[jonthewayne]

The Prisma docs mention that it is recommended to always explicitly call prisma.disconnect() in our code. Your quickstart example shows that, but when I checked out your aws lambda example, it didn't show it.

https://github.com/prisma/prisma-examples/tree/master/deployment-platforms/aws-lambda

We're deploying to AWS lambda and I wanted to double check with you what we should do.

We're actually using graphql-yoga server in our lambda function, so it'd be wonderful to have an example for how to add this to the server invocation in some way.

Thank you!

[2color]

Hey @jonthewayne,

That recommendation applies in the context of a long-running Node.js process that uses Prisma Client.

In the context of AWS Lambda, and more broadly serverless environment, it's ok not disconnect so that further invocations of the Serverless function can reuse the DB connection.

It's worth noting that reusing the connection, i.e. omitting the disconnect call, in Serverless functions has its limits, as it can exhaust the connection pool depending on your traffic pattern and concurrency limit (the number of serverless functions that can be invoked simultaneously).

For a more elaborate explanation of the considerations, check out the Serverless deployment docs

[jonthewayne]

Thanks Daniel!

[jonthewayne]

I can confirm that when using Graphql Yoga server, and passing in prisma via the server context, it will hang and spit back a 502 internal server error unless I actually use prisma.disconnect() in the resolver. If I use it, function is super quick, works repeatedly.

I tried creating a middleware that would call context.prisma.disconnect() after every resolver, but it must hang before this point, because that didn't work.

[2color]

Link to the related issue: #2241

[2color]

The fix for this, as detailed in #2241 (comment) is to set the the context.callbackWaitsForEmptyEventLoop of the AWS Lambda Context Object to false as follows:

exports.server = (event, context, cb) => {
  // Set to false to send the response right away when the callback executes, instead of waiting for the Node.js event loop to be empty.
  context.callbackWaitsForEmptyEventLoop = false

  return lambda.graphqlHandler(event, context, cb)
}