JSON parsing issue

[yocontra]

Just tried to run this for the first time and got this on pressing ctrl-c, not sure how to debug it further for ya:

analysing data
events.js:183
      throw er; // Unhandled 'error' event
      ^

Error: Unexpected COMMA(",") in state COLON
    at Parser.proto.parseError (/Users/contra/.nvm/versions/node/v8.9.4/lib/node_modules/clinic/node_modules/jsonparse/jsonparse.js:321:16)
    at Parser.proto.onToken (/Users/contra/.nvm/versions/node/v8.9.4/lib/node_modules/clinic/node_modules/jsonparse/jsonparse.js:395:24)
    at Parser.parser.onToken (/Users/contra/.nvm/versions/node/v8.9.4/lib/node_modules/clinic/node_modules/JSONStream/index.js:126:12)
    at Parser.proto.write (/Users/contra/.nvm/versions/node/v8.9.4/lib/node_modules/clinic/node_modules/jsonparse/jsonparse.js:139:34)
    at Stream.<anonymous> (/Users/contra/.nvm/versions/node/v8.9.4/lib/node_modules/clinic/node_modules/JSONStream/index.js:21:12)
    at Stream.stream.write (/Users/contra/.nvm/versions/node/v8.9.4/lib/node_modules/clinic/node_modules/through/index.js:26:11)
    at TraceEventDecoder._transform (/Users/contra/.nvm/versions/node/v8.9.4/lib/node_modules/clinic/node_modules/@nearform/clinic-doctor/format/trace-event-decoder.js:114:19)
    at TraceEventDecoder.Transform._read (_stream_transform.js:186:10)
    at TraceEventDecoder.Transform._write (_stream_transform.js:174:12)
    at doWrite (_stream_writable.js:387:12)

then looking at the folder, it spit out 30+ folders:

might have something to do with happypack running a bunch of subprocesses

[AndreasMadsen]

might have something to do with happypack running a bunch of subprocesses

Yep, that sounds reasonable. What do you think the expected behavior should be?

[AndreasMadsen]

As for the Error: Unexpected COMMA(",") in state COLON issue. There is unfortunately some bugs in node.js v8.9.4, we have fixed then but node.js v8.10.0 hasn't been released yet.

You can try with node.js v9.4.0 that should work better.

[yocontra]

From what I'm seeing is that when the traces get very large this error pops up - if it's a node 8 thing I'll close it and try with node 9.

[gboysko]

I'm using the latest clinic doctor with Node.js 9.5.0 and am getting a slightly different JSON error during analysis:

^Canalysing data
events.js:137
      throw er; // Unhandled 'error' event
      ^

Error: Invalid JSON (Unexpected "\"" at position 20385 in state STOP)
    at Parser.proto.charError (/Users/boysko/.nvm/versions/node/v9.5.0/lib/node_modules/clinic/node_modules/jsonparse/jsonparse.js:90:16)
    at Parser.proto.write (/Users/boysko/.nvm/versions/node/v9.5.0/lib/node_modules/clinic/node_modules/jsonparse/jsonparse.js:284:26)
    at Stream.<anonymous> (/Users/boysko/.nvm/versions/node/v9.5.0/lib/node_modules/clinic/node_modules/JSONStream/index.js:21:12)
    at Stream.stream.write (/Users/boysko/.nvm/versions/node/v9.5.0/lib/node_modules/clinic/node_modules/through/index.js:26:11)
    at TraceEventDecoder._transform (/Users/boysko/.nvm/versions/node/v9.5.0/lib/node_modules/clinic/node_modules/@nearform/clinic-doctor/format/trace-event-decoder.js:114:19)
    at TraceEventDecoder.Transform._read (_stream_transform.js:185:10)
    at TraceEventDecoder.Transform._write (_stream_transform.js:173:12)
    at doWrite (_stream_writable.js:407:12)
    at writeOrBuffer (_stream_writable.js:393:5)
    at TraceEventDecoder.Writable.write (_stream_writable.js:290:11)

Would it help if I sent you the generated files?

[davidmarkclements]

@gboysko are you using the cluster module?

[gboysko]

I'm using the sticky-cluster module in my application (which uses cluster internally). So, I guess, yes. Is that a limitation?

[AndreasMadsen]

@gboysko Each process will write to the same file which is causing issues. We are working on fixing it in nodejs/node#18480 – However, even when "fixed" it won't be obvious what data from what process you want to be analyzed. Thus the best thing will properly always be to benchmark a single standalone-worker.

[AndreasMadsen]

I created an issue to track the cluster issue: https://github.com/nearform/node-clinic-doctor/issues/102

[gboysko]

Thanks @AndreasMadsen. I can startup my application with a single worker process, but don't know if I could instruct Clinic to only monitor it. Is that possible? I could add calls directly into the child process workflow if the command line tool doesn't have the ability.

[AndreasMadsen]

For the moment you need to run the worker without a master process. If the master is decoupled from the worker by using exec in cluster.setupMaster then that should be fairly easy.

There is unfortunately very little we can do until nodejs/node#18480 is merged – and I'm having a lot of trouble with operating systems that are not easily accessible to me 🙄

[gboysko]

I see. I'll see what I can do to restructure my application to use a single process. Thanks!

[gboysko]

@AndreasMadsen My application runs in several different clustering options (vertical, horizontal) as well as "none". When "none" is selected, a single process is used. However, in this configuration, I still get a failure. Note that my application still loads the cluster module, but it never "forks" a child process. Would you expect me to see the same JSON parsing error? Do I need to eradicate the cluster module from my source code to use this tool?

[AndreasMadsen]

Note that my application still loads the cluster module, but it never "forks" a child process.

That should be fine.

/cc @mafintosh You could help solve this issue?