Profiling with ts-node / express

[anuraagy]

Problem Statement

We have an express/node/typescript backend and we set up Sentry profiler. However, most of the functions are showing up in the profiler with name "fulfilled" or "__awaiter". Any idea why that might be happening?

We use ts-node to run our application!

Solution Brainstorm

No response

Product Area

Profiling

[getsantry[bot]]

Assigning to @getsentry/support for routing ⏲️

[getsantry[bot]]

Routing to @getsentry/product-owners-profiling for triage ⏲️

[JonasBa]

@anuraagy that is the result of TS transpiling async/await expressions. I made a quick reproduction here where you can see the resulting expressions being transpiled from async/away

[anuraagy]

HI @JonasBa , thank you for the response. Is there any way around this? At this point the profiler isn't super useful because we don't have the function level insights anymore.

[JonasBa]

@anuraagy I need to take some time and see what might be some possible workarounds. Would you mind sharing how these frames look like in the profiling product?

[anuraagy]

Everything is nested under fulfilled. Is this helpful?

[JonasBa]

@anuraagy Yes, thanks for sharing! This is sadly a limitation of async/await implementation inside v8. There is a good explanation here, but the tldr is that async await stack traces arent really a single stack trace and are actually spread out over time, hence why you seem them all being disconnected at the fulfilled frame (where async happens).

In such cases, we would suggest you to focus on the aggregate flamegraph and look for functions with high sample count. The main idea here is that by optimizing functions that are often occupying the call stack, you can still improve the runtime of the program without focusing on its chronological execution