Re: [PATCH v3] mingw: workaround for hangs when sending STDIN

[Junio C Hamano <gitster@pobox.com>]

"Alexandr Miloslavskiy via GitGitGadget" <gitgitgadget@gmail.com>
writes:

> From: Alexandr Miloslavskiy <alexandr.miloslavskiy@syntevo.com>
>
> Explanation
> -----------
> The problem here is flawed `poll()` implementation. When it tries to
> see if pipe can be written without blocking, it eventually calls
> `NtQueryInformationFile()` and tests `WriteQuotaAvailable`. However,
> the meaning of quota was misunderstood. The value of quota is reduced
> when either some data was written to a pipe, *or* there is a pending
> read on the pipe. Therefore, if there is a pending read of size >= then
> the pipe's buffer size, poll() will think that pipe is not writable and
> will hang forever, usually that means deadlocking both pipe users.
> ...
> Chosen solution
> ---------------
> Make `poll()` always reply "writable" for write end of the pipe.
> Hopefully one day someone will find a way to implement it properly.
>
> Reproduction
> ------------
> printf "%8388608s" X >large_file.txt
> git stash push --include-untracked -- large_file.txt
>
> I have decided not to include this as test to avoid slowing down the
> test suite. I don't expect the specific problem to come back, and
> chances are that `git stash push` will be reworked to avoid sending the
> entire patch via STDIN.
>
> Signed-off-by: Alexandr Miloslavskiy <alexandr.miloslavskiy@syntevo.com>
> ---

Thanks for a detailed description.

I notice that we saw no comments from Windows experts for these
three rounds.  Can somebody give an Ack (or nack) on it at least?

I picked obvious "experts" in the output from 

    $ git shortlog --since=1.year --no-merges master compat/ming\* compat/win\*

Thanks.