os: Windows: reading data from stdin hangs in 1.9

[mappu]

Hi,

What version of Go are you using (go version)?

go1.9.1 windows/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

Windows 10 amd64

What did you do?

I have a program that

• uses github.com/Microsoft/go-winio to listen on a named pipe (maybe that's relevant, i don't know)
• uses CGO, using Cygwin's distribution of mingw-w64 gcc, but not targeting Cygwin, nor running under it
• expects to read some data from stdin shortly after it launches

What did you expect to see?

The Go program should receive data on stdin, then go about its business, as expected.
This works as expected on Go 1.8.4.

What did you see instead?

The Go program hangs at 0% CPU usage.
From the behaviour of the program i infer it is blocked on reading from stdin.
It hangs probably 5/10 attempts when launched via a Qt application, but interestingly it hangs 0/10 attempts when launched from cmd.exe.

This issue is almost identical to #22024, but my case is a bit different, because

• I am not targeting cygwin, nor running under cygwin
• The hang is intermittent (maybe a race condition?)
• I do not yet have a short reproducer

[ianlancetaylor]

CC @alexbrainman

[ghost]

https://github.com/Microsoft/go-winio

In the final paragraph of the Readme.md file is a citation to another Go named pipe implementation.

[as]

The issue seems to be converging on how Go (and perhaps the new poller) interacts with named pipes. Cygwin uses named pipes as a conduit for data that would flow through anonymous pipes between two processes under certain conditions mentioned in #22024

[as]

@forskning The difference is that Microsoft package seems to support additional functionality.

On Windows, named pipes can transfer data in message mode or byte mode. The original npipe didn't support message mode. Cygwin on the other hand, uses message mode.

@mappu

In lieu of a short reproducible snippet, Are you able to share any information on how the pipe is created using that package? Specifically, the mode used (message or byte), and whether this affects your ability to reproduce the issue in your application.

[alexbrainman]

@mappu it is difficult to suggest anything without reproducible example. Even non reproducible example would be better than what you have provided - vague description of what you think your program does.

Alex

[gopherbot]

Change https://golang.org/cl/69871 mentions this issue: internal/poll: only call SetFileCompletionNotificationModes for sockets

[alexbrainman]

@mappu can you, please, try https://golang.org/cl/69871 to see if it fixes your problem?

Thank you

Alex

[gopherbot]

Change https://golang.org/cl/70990 mentions this issue: [release-branch.go1.9] internal/poll: only call SetFileCompletionNotificationModes for sockets