Support printing backtrace also on SIGTERM

[orgads]

What is the problem this feature will solve?

PR #29207 added support for --trace-sigint. A similar feature can be very useful for SIGTERM as well. When running on k8s, if liveness probe doesn't respond, the pod is terminated using SIGTERM. It can be very useful to have a trace in case the application is stuck in an infinite loop.

What is the feature you are proposing to solve the problem?

Add --trace-sigterm to print a trace on SIGTERM.

What alternatives have you considered?

No response

[RobsonTrasel]

Hi @orgads

In Node.js version 23, the Diagnostic Report feature is available and can greatly assist with debugging when a process receives a SIGTERM. You can either enable it using the --diagnostic-report-on-signal flag or implement a custom SIGTERM handler that generates the report. This report includes a stack trace along with other process details, providing valuable insights into what was happening at the time of termination.

Below is an example of a custom SIGTERM handler:

process.on('SIGTERM', () => {
  const reportPath = process.report.writeReport();
  console.error(`Diagnostic report generated at: ${reportPath}`);
  process.exit(1);
});

This approach generates a detailed diagnostic report at the moment SIGTERM is received, which should help with debugging issues in your application.

[orgads]

Thank you @RobsonTrasel

The flag was renamed --report-on-signal and also requires --report-signal=SIGTERM.

But it doesn't work when the application is stuck in an infinite loop. process.on is not called, and also this flag doesn't report anything. Tested with 23.7.0.

function bar() {
  let num = 0;
  for (;;) {
    ++num;
  }
  console.log(num);
}

function foo() {
  bar();
}

process.on('SIGTERM', () => {
  const reportPath = process.report.writeReport();
  console.error(`Diagnostic report generated at: ${reportPath}`);
  process.exit(1);
});

foo();

node --report-on-signal --report-signal=SIGTERM trace.mjs &
kill -TERM %1
# Nothing happens, the app is not even terminated :(

[theanarkh]

Maybe you can implement this by addon.