Re: mkfifo buffer exhibiting unexpected behaviour

[Rich Felker <dalias@libc.org>]

On Wed, Jan 16, 2019 at 08:08:00PM -0500, Steven Hum wrote:
> Running this simple test using clock from sutils to produce a repeating one second interval input stream..
> 
> mkfifo fifo
> clock -i 1 -sf "T> stream one" >fifo &
> clock -i 1 -sf "D> stream two" >fifo &
> cat fifo
> 
> on void musl only the second fifo input stream is displayed.
> on void glibc, both input streams are displayed interleaved as expected.
> 
> Are fifo buffers handled differently under musl?

No, aside from possible stdio buffering it's entirely a kernel matter.
I looked up the sutils source and see it's flushing after each output,
and tried it on an Alpine-based box here (with musl) and could not
reproduce what you're seeing. Both outputs are visible and roughly
interleaved (although their order sometimes swaps with scheduling, of
course).

Rich