bug#56025: 29.0.50; em-extpipe-test-2 times out on EMBA and Cygwin

[Sean Whitton]

Hello,

On Fri 17 Jun 2022 at 09:39am -04, Ken Brown wrote:

> On 6/16/2022 6:01 PM, Ken Brown wrote:
>> On 6/16/2022 3:30 PM, Sean Whitton wrote:
>>> Hello Ken,
>>>
>>> On Thu 16 Jun 2022 at 02:30pm -04, Ken Brown wrote:
>>>
>>>> In commit 231a1ba3, Lars disabled the extpipe tests on EMBA "because they
>>>> apparently time out".  The EMBA log he cited in the commit message shows 
>>>> that
>>>> only em-extpipe-test-2 times out.  And this same test (but no others) also 
>>>> times
>>>> out on Cygwin:
>>>
>>> That test invokes `sh -c "rev >temp"` as its only subprocess, so that's
>>> probably what is timing out.  Is there something different about
>>> Cygwin's sh?  Something about EOFs?
>>
>> I'm not aware of anything different.  Here's what happens when I run the test
>> interactively:
>>
>> $ time echo \"bar\" | sh -c "rev >temp"
>>
>> real    0m0.100s
>> user    0m0.030s
>> sys     0m0.030s
>>
>> $ cat temp
>> "rab"
>>
>> And keep in mind that the test also times out on EMBA.
>
> I just tried a different experiment: In an interactive emacs-29 session, I
> started eshell and typed
>
>    echo \"bar\" | rev *>temp
>
> Nothing visible happens until I type 'C-c C-c'.  Then a prompt appears again,
> and 'ls -l' shows that temp exists and is empty.
>
> Prior to typing 'C-c C-c', 'M-x list-processes' (or 'C-c C-s') shows a bash
> process running but it doesn't show 'rev'.  But running 'ps' outside of emacs
> shows both 'rev' and its parent 'bash' process.
>
> It does seem that there's an actual bug here, not just a test that should be
> skipped because it times out.  It could be a Cygwin bug, of course, but that
> doesn't explain the EMBA failure.

Could you see if the same thing happens if you type

    echo "bar" | sh -c "rev >temp"

into an interactive session, please?

If it's the same then extpipe has uncovered a general Eshell bug.

-- 
Sean Whitton