souremaps arent being applied

[mbrevda]

Hi - trying to run speedscope to help optimize program startup. It doesn't seem like sourcemaps are being applied, making tracing operations challenging.

Here is a standalone script that closely mimics my setup, illustrating the issue:

test.sh

set -e
tmpdir=$(mktemp -d)

cat << EOF > $tmpdir/bar.ts
import http from "node:http";
function listenCallBack() {
  console.log("Server is running");
  setTimeout(() => {
    console.log("exiting server...");
    process.exit(0);
  }, 100);
};

const server = () => {
  const server = http.createServer((req, res) => {
    res.end("Hello World");
  });
  server.listen("8080", listenCallBack);
  return server;
};

export default server;
EOF

cat << EOF > $tmpdir/index.ts
import('./bar.ts').then((bar) => bar.default());
EOF

cd $tmpdir

npx esbuild --bundle --splitting --minify --sourcemap=linked --platform=node --format=esm --out-extension:.js=.mjs --outdir=./ index.ts

node --prof --enable-source-maps $tmpdir/index.mjs
node --prof-process --preprocess -j isolate*.log | npx speedscope -
rm -rf $tmpdir

Thanks!

[jlfwong]

Hey! As far as I remember, there's no circumstance where source-maps are automatically applied. That said, speedscope lets you apply sourcemaps after-the-fact.

See #317

[mbrevda]

speedscope lets you apply sourcemaps after-the-fact.

Thats cool! Unfortunately, dropping sourcemaps doesn't seem to have any effect on paths or symbols. Is there another way to load them that I can try?

[mbrevda]

Could this be related to esm code? I tried generating my code as .js (from .mjs) but that didn't help. Any way to debug sourcemaps to see if they are finding anything to apply?

[jlfwong]

I'm not sure offhand if this would have anything to do with esm!

If you want to debug, your best bet would be to step through the code here:

speedscope/src/lib/js-source-map.ts

Line 75 in de17f12

let fileMatches = false

To get up and running locally, check out https://github.com/jlfwong/speedscope/blob/main/CONTRIBUTING.md

[mbrevda]

Good call! It seems that the prof traces aren't having their filename/line/column populated. Not sure if this is the best way to do it, but the following patch fixes that:

diff --git a/src/lib/profile.ts b/src/lib/profile.ts
index 4e04742..13b189b 100644
--- a/src/lib/profile.ts
+++ b/src/lib/profile.ts
@@ -66,6 +66,15 @@ export class Frame extends HasWeights {

   private constructor(info: FrameInfo) {
     super()
+    if (!info.file && !info.line && !info.col) {
+      const matches = info.name.match(/(?:\/\/?)?([^:]+):(\d+):(\d+)/)
+      if (matches) {
+        info.file = matches[1]
+        info.line = parseInt(matches[2], 10)
+        info.col = parseInt(matches[3], 10)
+      }
+    }
+
     this.key = info.key
     this.name = info.name
     this.file = info.file

However, even with this patch, the frames aren't remapped to their proper sources.