NODE_V8_COVERAGE does not fail gracefully when inspector is disabled

Version: master
Subsystem: inspector

$ ./configure --without-intl
$ make -j4
$ NODE_V8_COVERAGE=/tmp/foo ./node -p 42

currently yields

internal/bootstrap/loaders.js:131
      mod = bindingObj[module] = getInternalBinding(module);
                                 ^

Error: No such module: profiler
    at internalBinding (internal/bootstrap/loaders.js:131:34)
    at setupCoverageHooks (internal/bootstrap/pre_execution.js:122:3)
    at prepareMainThreadExecution (internal/bootstrap/pre_execution.js:21:7)

I feel like this should a) print some kind of helpful message and b) maybe only print a warning or so instead of failing to execute the script.

@bcoe

@bcoe

@addaleax

@addaleax I'd like to take a look at this. Up for the mentor-available thing. 😄

@shobhitchittora

@shobhitchittora Cool! As you can see from the stack trace, the function that sets up coverage is setupCoverageHooks in lib/internal/bootstrap/pre_execution.js, so that’s likely what you’d want to modify. There are also other examples of warnings being emitted in that file that you can take a look at.

As for contributing in general, https://github.com/nodejs/node/blob/master/doc/guides/contributing/pull-requests.md and https://github.com/nodejs/node/blob/master/doc/guides/writing-tests.md are probably helpful starting points. And if you run any trouble, feel free to ping me here or on Twitter or IRC (or generally feel free to ask a question in #node-dev on Freenode).

@addaleax

Thanks @addaleax for the code pointers. It's been some time since I pushed code here ( maybe in 2018 ), hope the guidelines are still the same.

Well! I see the docs and guidelines are much better organized now. Great work there!

@addaleax

I see that profiling logic has been recently moved to C++ land in #26874. Thinking as to why the reason the profiler binding is getting resolved here? Is something wrong with the bootstrapping here? @addaleax

@shobhitchittora

@shobhitchittora What’s wrong is that the profiler internal binding from C++ isn’t available when the inspector is disabled – that’s what’s causing the exception in the output that I posted.

One way (of multiple ones) to address this might be to watch out for such an exception in JS, and handle it appropriately rather than letting it crash the process.

Oh! Got it. I've added an try-catch block now and the output is as below -

>> NODE_V8_COVERAGE=/tmp/foo ./node -p 42
42
(node:12182) Warning: Profiler is not enabled.

bootstrap: adds exception handling for profiler bootstrap

bootstrap: add exception handling for profiler bootstrap

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NODE_V8_COVERAGE does not fail gracefully when inspector is disabled #29542

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NODE_V8_COVERAGE does not fail gracefully when inspector is disabled #29542

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Trott commented on Sep 13, 2019

shobhitchittora commented on Sep 13, 2019

addaleax commented on Sep 13, 2019

shobhitchittora commented on Sep 13, 2019

shobhitchittora commented on Sep 13, 2019

addaleax commented on Sep 13, 2019

shobhitchittora commented on Sep 13, 2019

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