make trace-events write to configurable sink #152

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1. mike-kaufman commented on Feb 20, 2018

   

   mike-kaufman

   on Feb 20, 2018

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   some overlap here w/ #163?
2. AndreasMadsen commented on Feb 20, 2018

   

   AndreasMadsen

   on Feb 20, 2018

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   I don’t think so. Trace Events is a provider for our UDTP (user defined tracking point) implementation. The other implementations will have their own sink mechanism (the kernel).

   PS: nodejs/node#18480 will land soon, so that will at least make it possible to write to an arbitrary file.
3. jasnell commented on May 4, 2018

   

   jasnell

   on May 4, 2018

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   Quick update on this: @ofrobots and I have been speaking about the possibility of using the inspector protocol to deliver trace events. Some work has already started in this direction with a PR to allow multiple concurrent inspector protocol sessions. There's a bit of work to do here but it should give us a number of solid options.
4. ofrobots commented on May 4, 2018

   

   ofrobots

   on May 4, 2018

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   Some updates from our side:

   • The tracing domain is part of the Chrome DevTools protocol, but it isn't available in Node just yet – it is implemented in Chrome and @eugeneo has been working on adding the Tracing domain to Node. We expect to open a PR for this shortly.
   • Until recently Node was limited to a single inspector connection. Eugene recently added support for multiple clients to connect to DevTools to consume trace data. This should allow multiple clients to connect to consume trace data.

   Once this is available, it would be fairly straightforward to write clients in JS, or otherwise, to connect and consume data. Here's a small program that I wrote that retrieves trace data. I tested this against Chrome – as node doesn't expose the Tracing domain through the inspector just yet.

   const CDP = require('chrome-remote-interface');
   
   async function main() {
     const client = await CDP();
   
     client.on('event', (message) => {
       console.log(message.method);
     });
   
     let result = await client.Tracing.start({ recordMode: 'recordContinuously', transferMode: 'ReturnAsStream'});
     client.Tracing.tracingComplete(async (params) => {
       const stream = params.stream;
       let eof = false;
       let num = 0;
       while (!eof) {
         const chunk = await client.IO.read({handle: stream, size: 128 * 1024});
         num++;
         console.log(`chunk ${num} eof:`, chunk.eof, 'data:', chunk.data.length);
         eof = chunk.eof;
       }
     });
     setTimeout(() => { client.Tracing.end(); }, 2000);
   }
   
   main().catch(console.error);

   🎉React with 🎉1Reacted by Andreas Madsen
5. mike-kaufman commented on May 4, 2018

   

   mike-kaufman

   on May 4, 2018

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   Having this data over CDP is really useful, but does it obviate desire to redirect trace events to a file/stream, e.g. via a command-line switch? Consuming CDP may be challenging in PaaS environments, due to network constraints, process constraints, ...
6. ofrobots commented on May 4, 2018

   

   ofrobots

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   File output would still be supported.

   👍React with 👍1Reacted by Mike Kaufman
7. gireeshpunathil commented on Oct 25, 2019

   

   gireeshpunathil

   on Oct 25, 2019

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   should this remain open? [ I am trying to chase dormant issues to closure ]
8. jasnell commented on Oct 25, 2019

   

   jasnell

   on Oct 25, 2019

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   This can be closed
9. jasnell

   closed this as completedon Oct 25, 2019