process.stdout and process.stderr get flushed out-of-order in Windows when piped

[cowboy]

When process.stdout and process.stderr are not piped, writes to them are output in order, as written. When piped, they are written out-of-order. While there seems to be a workaround for the draining issue in #3584, I can't figure out a workaround for this issue.

Given this translation-party.js file:

// Test code
var words = "this is a happy test sentence of words".split(" ");

// Test code
for (var i = 0; i < words.length; i += 2) {
  process.stdout.write("[stdout] " + words[i] + "\r\n");
  process.stderr.write("[stderr] " + words[i + 1] + "\r\n");
}

In Windows, I see the following behavior.

C:\test>node translation-party.js
[stdout] this
[stderr] is
[stdout] a
[stderr] happy
[stdout] test
[stderr] sentence
[stdout] of
[stderr] words

C:\test>node translation-party.js | find "std"
[stdout] this
[stderr] is
[stderr] happy
[stderr] sentence
[stderr] words
[stdout] a
[stdout] test
[stdout] of

Can you guys please prioritize fixing these stdio piping issues?

[pipobscure]

try

node translate.js 2>&1 | find std

because what you are doing is letting node output to stderr and find to std out if I'm not mistaken.

On 20 Sep 2013, at 14:33, Ben Alman [email protected] wrote:

When process.stdout and process.stderr are not piped, writes to them are output in order, as written. When piped, they are written out-of-order. While there seems to be a workaround for the draining issue in #3584, I can't figure out a workaround for this issue.

Given this translation-party.js file:

// Test code
var words = "this is a happy test sentence of words".split(" ");

// Test code
for (var i = 0; i < words.length; i += 2) {
process.stdout.write("[stdout] " + words[i] + "\r\n");
process.stderr.write("[stderr] " + words[i + 1] + "\r\n");
}
In Windows, I see the following behavior.

C:\Users\Administrator\Desktop\grunt>node translation-party.js
[stdout] this
[stderr] is
[stdout] a
[stderr] happy
[stdout] test
[stderr] sentence
[stdout] of
[stderr] words

C:\Users\Administrator\Desktop\grunt>node translation-party.js | find "std"
[stdout] this
[stderr] is
[stderr] happy
[stderr] sentence
[stderr] words
[stdout] a
[stdout] test
[stdout] of
Can you guys please prioritize fixing these stdio piping issues?

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[cowboy]

Derp. Thanks!

C:\test>node translation-party.js 2>&1 | find "std"
[stdout] this
[stderr] is
[stdout] a
[stderr] happy
[stdout] test
[stderr] sentence
[stdout] of
[stderr] words

I'll close the issue. But PLZ OMG FIX #3584 THX

[nimhawk]

Run using cmd.exe and periodically get it out of order...

C:\devenv\workspace\sandbox\node-exit\test\fixtures>node translation-party.js 2>
&1 | grep "std"
[stdout] this
[stderr] is
[stderr] happy
[stdout] a
[stderr] sentence
[stdout] test
[stderr] words
[stdout] of

C:\devenv\workspace\sandbox\node-exit\test\fixtures>

[bdukes]

In powershell, I occasionally get out of order results (I'm piping to % { "$_" } per http://stackoverflow.com/a/12866669/2688, to get Powershell to avoid thinking the stderr output means the command failed):

C:\tmp\node-issue-6249
> node .\translation-party.js 2>&1 | % { "$_" }
[stdout] this
[stderr] is
[stdout] a
[stderr] happy
[stdout] test
[stderr] sentence
[stderr] words
[stdout] of
C:\tmp\node-issue-6249
> node .\translation-party.js 2>&1 | % { "$_" }
[stdout] this
[stderr] is
[stdout] a
[stderr] happy
[stdout] test
[stdout] of
[stderr] sentence
[stderr] words

[cowboy]

I'm going to reopen this, it might be a real bug.

[pipobscure]

I dont think there is actually a way to ensure the streams are in sync unless you ensure between writes that the receiving app has had a processing timeslice and has read its fd.

Because the other side might actually poll in reverse/random/unknown order.

I might be totally off base. I have been way too far away from the OS these days.

[cowboy]

Having stdout and stderr output in a predictable order qualifies as "really, really important" for something that bothers to make a distinction between stdout and stderr.

[FeodorFitsner]

You might want to check this: mapnik/node-mapnik#257 (comment)

[Fishrock123]

Fixed by nodejs/node@20176a9 a couple years ago.