export v8 trace API#42462
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Not sure we should do this. I mean, I generally prefer this, but when we added that trace API it was with the agreement with the v8 team that we would not expose a public API for it since they might still want to make changes to the underlying mechanism and exposing the public apis would make that more difficult.
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Thanks for the reply. |
export v8 trace api, so user can use it to trace custom events and collect the data by using inspector or the trace_events.createTracing method
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We spoke about this issue yesterday on the TSC call and landed on not wanting to expose this API right now, for more reasons then just the agreement with v8 that we wouldn't. The trace event mechanism in node is not super well maintained and has a good number of issues that will need to be addressed. Before we do more with it, and especially before we introduce apis that have to be supported long term, we should ensure the internal implementation is improved and made more robust. |
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Could you point me to the C++ part of the tracing API? I wasn't aware that we made that available in the V8 API. Generally though, Chrome's tracing system has a fairly stable and simple API: |
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Here's the view from our vendored in v8 history for this: https://github.com/nodejs/node/commits/master/deps/v8/src/builtins/builtins-trace.cc Ultimately, I'd really like to see the trace event system in Node.js get replaced with Perfetto with a fully supported API we can expose to users. If v8 doesn't mind us exposing an API here, then awesome, but we still need someone to dig in on the trace event subsystem and get it stable and out of experimental. |
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Thanks for the reply, do i need to close this PR ? |
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@theanarkh ... for now, yeah, this PR can be closed. But, if trace events are something that are of interest to you, I'd strongly encourage you to consider helping get the internals updated and in a better shape! In the meantime, we can work with the v8 folks to come up with a strategy around the api that we can be sure they have no problem supporting long term :-) |
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Ok I didn't know this was exposed as a Builtin in V8, which is far from ideal. What speaks against implementing this purely on node-side and use perfetto there directly? |
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The reason we originally went with the builtin approach was purely performance motivated. The builtin was a whole lot faster at the time it turned out. That said, I think we could absolutely go with a node+perfetto based solution here... we just need someone to do the work to get perfetto integrated. I had started work in that direction a while back but couldn't seem to get folks interested in advancing it forward: #35900 |
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Thanks, i will try my best to do that. |
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export v8 trace API, so user can use it to product custom trace events and collect it by inspector or trace_events.createTracing
make -j4 test(UNIX), orvcbuild test(Windows) passes