`enableShutdownHooks` usage interrupts writing logs via external logger

[dnechay]

Is there an existing issue for this?

• I have searched the existing issues

Current behavior

When using pino as logger for application and enableShutdownHooks, Nest doesn't wait for it to write all logs before exiting.

If app.enableShutdownHooks() is not used and shutdown hooks added manually on process.once for SIGINT/SIGTERM/etc, then pino is able to finish its logging, but if we enable Nest.js shutdown hooks - there is something under the hood that has impact on pino finalization.

Would be nice to understand what is the conflict and how to avoid it to support both.

Minimum reproduction code

https://codesandbox.io/p/devbox/recursing-lamarr-qjh9hh

Steps to reproduce

1. Clone/fork code
2. npm install
3. npm start
4. Wait app until app is up and running
5. Press Ctrl+C or send kill -2/kill -15 to pid

Expected behavior

Nest shutdown process doesn't interrupt pino to write all necessary logs that are buffered.

NestJS version

11.1.9

Packages versions

{
  "@nestjs/common": "^11.1.9",
  "@nestjs/core": "^11.1.9",
  "@nestjs/platform-express": "^11.1.9",
  "pino": "^10.1.0",
  "pino-pretty": "^13.1.2",
  "reflect-metadata": "^0.2.2",
  "rxjs": "^7.8.1"
}

Node.js version

v20.12.1 (and others)

In which operating systems have you tested?

• macOS
• Windows
• Linux

Other

No response

[mag123c]

After investigation, the root cause is process.kill(process.pid, signal) at nest-application-context.ts.

Pino v7+ relies on the 'exit' event to synchronously wait for its worker thread to flush logs.
However, process.kill(process.pid, signal) does not trigger the 'exit' event properly, causing logs to be lost.

If changed to exit, changes would be a breaking change because

1. Exit codes would change (e.g., SIGTERM: 143 → 0)
2. Other libraries' signal handlers would not be triggered
3. Orchestrators (Kubernetes, Docker, PM2) may behave differently

Perhaps NestJS could provide an option like enableShutdownHooks({ useProcessExit: true }) for users who need proper 'exit' event triggering for async loggers?

Reference: pinojs/pino#2002

[kamilmysliwiec]

@mag123c sounds good

[kamilmysliwiec]

Let's track this here #15986