FlameGraph VS WebKit

We'll use async-profiler and flame graphs for profiling. To simplify the process, we'll run the code using JBang.

And flame graphs excel and this kind of thing

https://www.brendangregg.com/flamegraphs.html

which can output in a format understood by Brendan Gregg's flame frames (https://www.brendangregg.com/flamegraphs.html)

But that's not quite the kind of tracing you're talking about. We also built a printf-style interface to our recording files, which seems closer:

Strategies included discontinuing or resizing underutilized services, transitioning to more cost-effective solutions, reducing the current resources to the amount of resources that we need for our application, and conducting detailed analyses of computing resource utilization through tools like flamegraphs. This detailed scrutiny helped identify and rectify significant cost-driving areas, such as garbage collection and application configurations.

Flame Graphs by Brendan Gregg

Historically brendangregg's since AIUI he basically invented flamegraphs

https://www.brendangregg.com/flamegraphs.html

So if you can make your tool eat whatever https://github.com/brendangregg/FlameGraph is fed with you're going to support a lot of existing tooling across OSes and languages.

“Flame graphs are a visualization of hierarchical data, created to visualize stack traces of profiled software so that the most frequent code-paths to be identified quickly and accurately.”

SVGs are amazing for interactive visualisation too. Like Flamegraphs: https://www.brendangregg.com/flamegraphs.html

This may be a good example of the application of a flame graph but it is not a good demonstration of flame graphs; the graph is nearly incidental. The source has an actual explanation.

A profiling flame graph from Graphile Crystal (a precursor to Grafast) using GraphQL.js' executor (each tick is 1ms, total: 29ms). As we removed more and more responsibilities from GraphQL.js, we ended up only using it for output. Replacing this final responsibility with a custom implementation in Graphile Crystal itself, we reduced execution time for this query down to 15.5ms (effectively removing the majority of the yellow portion of the flame graph).

Multiple engineers are working on adding it back: https://github.com/WebKit/WebKit/pulls?q=is%3Apr+is%3Aclosed...

Since 2023 Chrome announced the View Transition API, and it looks like Safari is also going to support it soon.

One heap per type.

Here’s an allocator optimized for that use case.

https://github.com/WebKit/WebKit/blob/main/Source/bmalloc/li...

To use this in Bun, you’d have to start Bun with the environment variable “BUN_JSC_useDollarVM=1” and then $vm.createBuiltin(mySourceCodeString)

When using this intrinsic, if any of the arguments are incorrect or it cannot otherwise enable it, the entire process will probably crash. In debug builds of JSC it will have a nicer assertion failure but that is not enabled in release builds

Example code: https://github.com/WebKit/WebKit/blob/17351231b4dedb62d81721...

also happy to answer any questions about Bun

Ah, good, let me introduce you to the wonderful world of the Chrome Devtools Protocol! (fka Chrome Remote Debugging Protocol)

I love this API for almost everything browser related. I built my RBI product atop this (BrowserBox: https://dosyago.com), and I think it's a drastically underrated API.

Also, it works out of the box in Edge, Brave, Chromium, and many parts of CRDP are supported by Firefox and Safari^1

1: See for example: https://github.com/WebKit/webkit/tree/main/Source/JavaScript...

No, it's unrelated.

https://github.com/WebKit/WebKit/commit/064df1a9f395f8c6e32c...

It's being worked on now: https://github.com/WebKit/WebKit/pull/17320

It is different. The cross-site navigation flag is a couple of years old. It was enabled by default for iOS in November 2018 for example https://github.com/WebKit/WebKit/commit/e191fc8c412850cb9fd0...