Bogus exit code 127 from a child process

[Alexey Izbyshev]

On 2024-03-17 12:27, Takashi Yano wrote:
> On Sun, 17 Mar 2024 12:01:55 +0300
> Alexey Izbyshev wrote:
>> On 2024-03-17 11:44, Takashi Yano wrote:
>> > On Sun, 17 Mar 2024 11:14:16 +0300
>> > Alexey Izbyshev wrote:
>> >> Hello,
>> >>
>> >> I've been getting occasional "Error 127" from make -jN on seemingly
>> >> random jobs. After reducing the set of jobs and eventually eliminating
>> >> make, I've arrived to this one-liner:
>> >>
>> >> bash -c 'true & true & wait -n || echo 1: $? && wait -n || echo 2: $?'
>> >>
>> >> When run repeatedly, the second "wait -n" often reports 127.
>> >>
>> >> I've reproduced this in the following environments:
>> >>
>> >> * Cygwin 3.5.1, Windows 10 22H2 x64
>> >> * Cygwin 3.4.6, Windows 10 22H2 x64 and Windows 7 x64
>> >>
>> >> I couldn't reproduce it in Cygwin 3.3.6 (WOW64) on Windows 7 x64.
>> >
>> > Could you please try latest cygwin 3.6.0 (TEST) ?
>> 
>> Tested with 3.6.0-0.82.gfc691d0246b9 on Windows 10 22H2 x64, the 
>> problem
>> still occurs.
> 
> In my evrironmen, trial for 1 hour does not reproduce the issue.
> Could you please let us know your environment, i.e. CPU, amount of
> memory, and so on?

It's been reproduced in a variety of environments:

* Windows 10 22H2 x64, Intel Core i7 11700, 32 GB RAM
* Windows 10 22H2 x64, Intel Core i7 9700, 32 GB RAM
* Windows 10 22H2 x64, Intel Core i7 6700, 32 GB RAM
* Windows 7 SP1 x64, Intel Core i7 6700, 32 GB RAM

I'm surprised that you're not hitting it very quickly. The following 
loop usually fails after a few iterations (rarely a hundred or so) in my 
tests:

while bash -c 'true & true & wait -n || { echo 1: $?; exit 1; } && wait 
-n || { echo 2: $?; exit 1; }'; do echo $((i++)); done

Thanks,
Alexey