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Occasional "No inspectable targets" error when launching chrome with a very short connectionPollInterval #145

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robbertbrak opened this issue May 24, 2019 · 3 comments · May be fixed by #191
Open

Occasional "No inspectable targets" error when launching chrome with a very short connectionPollInterval #145

robbertbrak opened this issue May 24, 2019 · 3 comments · May be fixed by #191

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@robbertbrak
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To reproduce, create and run a Node script such as the one below:

const chromeLauncher = require('chrome-launcher');
const CDP = require('chrome-remote-interface');

let opts = {
  connectionPollInterval: 2,
  chromeFlags: ['--headless'],
};

(async() => {
  for (let i = 0; i < 100; i++) {
    let chrome = await chromeLauncher.launch(opts);
    let client = await CDP({port: chrome.port});
    console.log(i, chrome.port);
    client.close();
    chrome.kill();
  }
})().catch(error => { 
  console.log(error); 
  process.exit(1) 
});

After an unpredictable number of loops, the script (usually) crashes with a stacktrace:

Error: No inspectable targets
    at defaultTarget (.../node_modules/chrome-remote-interface/lib/chrome.js:47:23)
    at Chrome._fetchDebuggerURL (.../node_modules/chrome-remote-interface/lib/chrome.js:188:32)
    at process.internalTickCallback (internal/process/next_tick.js:77:7)

It looks like chrome-launcher occasionally reports that the launched Chrome instance is ready and has a debugging port, even though it isn't actually ready to accept a debug session yet.
@patrickhulce
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Thanks very much for filing with a simple repro case!

That's correct chrome-launcher resolves as soon as Chrome has begun listening on the debugging port and not necessarily when a target/the requested launch page is available for inspection.

If you'd be interested in adding this functionality to chrome-launcher, I'd bet some other folks might end up making use of it as well :)

I imagine it just might involve polling http://127.0.0.1:<port>/json/list until it has an entry if you wanted to do it yourself.

@robbertbrak
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@patrickhulce It's great to get such a fast response!

But I'm a little unsure of what you're suggesting. Do you consider the issue I reported to be a bug or normal/expected behavior? In the latter case, would adding a flag (e.g. waitForInspectableTarget) to the launch options be an acceptable solution, or do you have something else in mind?

@patrickhulce
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Do you consider the issue I reported to be a bug or normal/expected behavior?

I consider it to be expected behavior, but I understand your use case is a common one that could be worthwhile to support in the library (waitForInspectableTarget sounds great to me 👍 ).

@gamtiq gamtiq mentioned this issue Oct 8, 2019
Closed
davidtaylorhq added a commit to discourse/discourse that referenced this issue Dec 12, 2019
@davidtaylorhq
DEV: Handle occasional 'No inspectable targets' error in run-qunit
43ca1bb 
This is to work around GoogleChrome/chrome-launcher#145
gamtiq added a commit to gamtiq/chrome-launcher that referenced this issue Mar 16, 2020
@gamtiq
feat: add waitForInspectableTarget option (fix GoogleChrome#145)
06aee79
@gamtiq gamtiq linked a pull request Mar 16, 2020 that will close this issue
Open
@pamelafox pamelafox mentioned this issue Sep 15, 2020
Merged
@anthonyec anthonyec mentioned this issue Oct 26, 2021
Merged
@cscheid cscheid mentioned this issue Oct 5, 2022
Closed
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feat: add waitForInspectableTarget option (fix #145) gamtiq/chrome-launcher
2 participants
@robbertbrak @patrickhulce