Stream JSON output (--json)

[simonflk]

This fixes #4629

What kind of change does this PR introduce?

bugfix

Did you add tests for your changes?

No. I will have a look and see if I can find where to add appropriate tests.

If relevant, link to documentation update:

Summary

This fixes an issue in #4629 where I reported that I was unable to write out profile JSON.

Does this PR introduce a breaking change?

I don't believe so, no.

Other information

[jsf-clabot]

All committers have signed the CLA.

[sokra]

I don't think using JSONStream will solve this issue. JSONStream uses JSON.stringify(item) internally. This does work in your example because it uses JSON.stringify(obj) instead of JSON.stringify(obj, null, 2). This generates a much smaller string.

Maybe just change to JSON.stringify(obj) which increases the limit. Or find a json stringifier which really stringifies in chunks.

[webpack-bot]

Thank you for your pull request! The most important CI builds succeeded, we’ll review the pull request soon.

[timse]

json-streamify looks like it does actually stream, but it comes at the cost of "lexing" and traversing a potentially huge json. not sure if thats good.

[sokra]

We can try JSON.stringify and if it throws use the safe json-stringify impl.

[avocadee]

I applied the change to webpack 1.13.0, node version v4.4.7, npm version 2.15.8
var stringify = require("JSONStream").stringify("", "", "");
stringify.pipe(process.stdout);
stringify.write(stats.toJson(outputOptions));
stringify.end();

But I got this error :(

stream.js:74
throw er; // Unhandled stream error in pipe.
^

RangeError: Invalid string length
at join (native)
at Object.stringify (native)
at Stream. (C:\XXXXXX\webpack\node_modules\JSONStream\index.js:196:23)
at Stream.stream.write (C:\XXXXXX\webpack\node_modules\JSONStream\node_modules\through\index.js:26:11)
at compilerCallback (C:\XXXXXX\webpack\node_modules\webpack\bin\webpack.js:175:14)
at Compiler. (C:\XXXXXX\webpack\node_modules\webpack\lib\Compiler.js:194:14)
at Compiler.emitRecords (C:\XXXXXX\webpack\node_modules\webpack\lib\Compiler.js:282:37)
at Compiler. (C:\XXXXXX\webpack\node_modules\webpack\lib\Compiler.js:187:11)
at C:\XXXXXX\webpack\patches\webpack\lib\Compiler.js:73:20
at Compiler.applyPluginsAsync (C:\XXXXXX\webpack\node_modules\webpack\node_modules\tapable\lib\Tapable.js:60:69)
at Compiler.afterEmit (C:\XXXXXX\webpack\patches\webpack\lib\Compiler.js:70:14)
at Compiler. (C:\XXXXXX\webpack\patches\webpack\lib\Compiler.js:65:27)
at C:\XXXXXX\webpack\node_modules\webpack\node_modules\async\lib\async.js:52:16
at replenish (C:\XXXXXX\webpack\node_modules\webpack\node_modules\async\lib\async.js:306:28)
at C:\XXXXXX\webpack\node_modules\webpack\node_modules\async\lib\async.js:326:29
at C:\XXXXXX\webpack\node_modules\webpack\node_modules\async\lib\async.js:44:16
at C:\XXXXXX\webpack\node_modules\webpack\node_modules\async\lib\async.js:1209:30
at C:\XXXXXX\webpack\node_modules\less\node_modules\graceful-fs\graceful-fs.js:43:10
at C:\XXXXXX\webpack\node_modules\webpack\node_modules\enhanced-resolve\node_modules\graceful-fs\graceful-fs.js:43:10
at FSReqWrap.oncomplete (fs.js:82:15)

[sokra]

https://twitter.com/bmeurer/status/889450001709096962