ts-node-dev hangs when creating PrismaClient

Bug description

When I construct a PrismaClient at the top level of my express server:

const prisma = new PrismaClient();

My server no longer restarts running under ts-node-dev when source files change. And if I try to manually kill the process via a SIGTERM, the process hangs.

I’ve confirmed the issue is caused by some interaction of ts-node-dev and PrismaClient, because when I run the same server with ts-node, I can kill the process just fine.

How to reproduce

Run a long-running server with a PrismaClient under ts-node-dev

Expected behavior

No response

Prisma information

N/A

Environment & setup

• OS: Ubuntu
• Database: PostgreSQL, but my DATABASE_URL is empty when observing this bug
• Node.js version: 10.19.0

Prisma Version

Environment variables loaded from .env
prisma               : 2.21.2
@prisma/client       : 2.21.2
Current platform     : debian-openssl-1.1.x
Query Engine         : query-engine e421996c87d5f3c8f7eeadd502d4ad402c89464d (at node_modules/@prisma/engines/query-engine-debian-openssl-1.1.x)
Migration Engine     : migration-engine-cli e421996c87d5f3c8f7eeadd502d4ad402c89464d (at node_modules/@prisma/engines/migration-engine-debian-openssl-1.1.x)
Introspection Engine : introspection-core e421996c87d5f3c8f7eeadd502d4ad402c89464d (at node_modules/@prisma/engines/introspection-engine-debian-openssl-1.1.x)
Format Binary        : prisma-fmt e421996c87d5f3c8f7eeadd502d4ad402c89464d (at node_modules/@prisma/engines/prisma-fmt-debian-openssl-1.1.x)
Default Engines Hash : e421996c87d5f3c8f7eeadd502d4ad402c89464d
Studio               : 0.371.0

[mgummelt]

@Sytten

Adding --exit-child does in fact work. Thank you!

I don’t understand why it works, unless prisma is somehow blocking SIGTERM, and this option overrides that.

I’m happy to switch to a more reliable solution than ts-node-dev if you have any suggestions. By accounts I’ve read, nodemon is too slow, since it recompiles the entire typescript project.

[pantharshit00]

@nghiepit I disagree, that is how it is implemented in ts-node-dev and I don’t think we can change anything to change the behaviour here.

Alternatively, try using the Node-API preview which doesn’t spawn a child process preventing this altogether: https://www.prisma.io/docs/concepts/components/prisma-engines/query-engine#enable-the-node-api-n-api-preview