Stream.pipeline() does not call the callback on completion

[matdodgson]

• Version: 12.18.0 and 14.4.0
• Platform: Ubuntu 20.04 LTS
• Subsystem:

I use the following code to test the callback of the pipeline() function under node 12.18.0 and node 14.4.0:

'use strict';

import {pipeline, Readable} from 'stream';
import {createWriteStream} from 'fs';

pipeline(
    Readable.from(['a', 'b', 'c', '\r\n']),
    process.stdout,
    (err) => {
        console.log('finish callback stdout');
    }
);

pipeline(
    Readable.from(['a', 'b', 'c', '\r\n']),
    createWriteStream('outfile.txt'),
    (err) => {
        console.log('finish callback file write stream');
    }
);

Under Node 12.18.0, the callback on the second pipeline() is called on completion, but the callback on the first is not.
Same problem on Node 14.4.0.

Related to #26550 and maybe also #33237

[jasnell]

@nodejs/streams

[ronag]

process.stdout + end() in pipe @vweevers. Maybe related #32373

[mcollina]

I thought #32373 was supposed to fix this.

[ronag]

This works as intended. The callback is called in both cases. At least on Node 14.

The stdout example doesn't print anything because pipeline closes stdout before the callback is invoked, hence the console.log (which uses stdout) doesn't do anything. Changing to console.error will properly print as expected.

[mcollina]

I think we can close.

[matdodgson]

Apologies - should have used better testing code! The problem is fixed in v14 (I assume #32373) so just waiting on the back port to v12.