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privatenumber
`node:assert`'s `assert.ok(false)` is really slow when using tsx
Acknowledgements
- [X] I read the documentation and searched existing issues to avoid duplicates
- [X] I understand this is a place to report a confirmed bug (not seek debugging help)
- [X] I understand this is a collaborative open source project, and relies on community contributions
- [X] I have read and understood the Contribution guide
Minimal reproduction
(sorry it's inline)
import assert from "node:assert/strict";
// An assert.ok(false) in a nested function with a ton of text (either code or comments) gets really slow.
// The more nested the function is, the slower it is.
// It doesn't happen with assert.equal(true, false), nor assert.ok(false, "message")
function f1() {
function f2() {
function f3() {
function f4() {
function f5() {
function f6() {
function f7() {
function f8() {
function f9() {
function f10() {
function f11() {
function f12() {
function f13() {
function f14() {
function f15() {
// Tons of commented out lines
//
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assert.ok(false);
}
f15();
}
f14();
}
f13();
}
f12();
}
f11();
}
f10();
}
f9();
}
f8();
}
f7();
}
f6();
}
f5();
}
f4();
}
f3();
}
f2();
}
f1();
Version
4.9.6
Node.js version
22.0.0
Package manager
pnpm
Operating system
Linux
Problem & expected behavior (under 200 words)
- What happened
When running node:assert's assert.ok(false) with tsx the automatic error message generation becomes notoriously slow.
It seems to get slower the larger the file is, and the deeper the function that call's assert.ok is.
I only tested this with an ESM package, running node --import tsx/esm repro.ts.
It is not slow if I compile the file and run it without tsx.
I have a strong belief that tsx is interfering with this function, making it really slow. As providing an error message to assert.ok works around the performance issue.
- What I expected
It should be approximately as fast as the compiled version.
- Error stack trace
No relevant stack traces.
- Documentation links
No relevant documentation links.
- Screenshots
No relevant screenshots.
- Other
Thanks for creating and maintaining this project.
Contributions
- [ ] I'm interested in working on this issue
- [ ] I'm willing to offer financial support
I may be able to help debug and/or fix this issue, as I'm quite familiar with Node's and v8's stack traces APIs, but I'm not familiar at all with tsx's internals.
I can confirm that the error is also present in v4.0.0 and other versions of node.
Thanks for the issue!
Would you mind moving the reproduction into a repo that compares the speed between tsx and node using hyperfine or even just time? Curious what you mean by "slow".
Here's the reproduction: https://github.com/alcuadrado/tsx-slow-assert-failure
It runs it on github actions so that you don't need to install it.
In this case, it runs 150 times slower, but we discovered this because of a real-life assert.ok(expression) taking about 30 seconds when the test was originally passing (before expression turned falsy) in ~4ms.
I boiled down the minimal reproduction further in https://github.com/privatenumber/node-bug-slow and reported it to Node.js: https://github.com/nodejs/node/issues/52962
