Force Sentry to wait for every captureException call

[cideM]

Problem Statement

I have been working with the Go SDK for a while now and it's very pleasant to use and even includes a Sync transport.

I am now working in a Javascript project that uses a framework which unfortunately calls process.exit quite often. As a result, Sentry errors never make it to our dashboard, since Sentry doesn't have time to flush the buffer. I thought I could just set some option and force Sentry to wait for every single captureException call

Solution Brainstorm

One potential workaround would be to overwrite process.exit and call Sentry.close() in there.

I thought that I could also provide a sync transport (there appears to be none) so I tried something very simple:

const makeTransport = (options: NodeTransportOptions): Transport => {
  return {
    send: (e: Envelope): Promise<TransportMakeRequestResponse> => {
      console.log("send", e) // <-- console.log that transport is working
      return Promise.resolve({
        statusCode: 200,
        headers: {
          "x-sentry-rate-limits": null,
          "retry-after": null,
        },
      });
    },
    flush: (timeout?: number): Promise<boolean> => {
      console.log("flush");
      return Promise.resolve(true);
    },
  };
};

Later in this file I am doing the following to trigger the custom transport:

Sentry.init({
  debug: true,
  enabled: true,
  dsn: "....",
  transport: makeTransport,
  attachStacktrace: true,
});
Sentry.captureException("test");

I'd expect to see something in my console that indicates that send was called, but I don't. Is there some buffering going on before my custom transport is called?

It seems that there is currently no way to force Sentry to wait until every single captureException call has finished.

[andreiborza]

Hello @cideM, I tried adding your makeTransport to a sample project of mine and I'm seeing the logs.

Could you please provide a sample reproduction repo?

Also, check out https://docs.sentry.io/platforms/javascript/configuration/transports/#custom-transport, we have a helper called createTransport that you could use.

Although, if your framework exits with process.exit I don't think flushing will be awaited.

[AbhiPrasad]

process.exit instructs Node.js to terminate synchronously and is designed to make the process exit as quickly as possible. All pending I/O operations (like a network request) will get cancelled. Only sync code can be run in process.on('exit', ...) as well.

Our transport creates and resolves promises (async code) as sending the event is I/O, and so therefore there never will be a strong guarantee that all events will get flushed. I recommend re-architecting the app so that a call to Sentry.flush is executed before the process is exited instead of trying to listen on process exit or change how the transport works.

[cideM]

We'll go with overwriting process.exit. I assume i was doing something wrong that made my example not work. Closing this.