On Wed, Oct 13 2021, Lars Ingebrigtsen wrote:

> Helmut Eller <eller.helmut@gmail.com> writes:
>
>> I would like to request this feature: stop-process, when called with a
>> sub-process that is connected via pipes, should use delete_read_fd.  It
>> should basically do the same as for sockets.
>>
>> Currently, stop-process uses some difficult to understand logic and
>> eventually sends SIGSTOP to the process.  This might work in theory, but
>> in practice it can take a long time before Emacs stops receiving output.
>
> You're supposed to be able to use `continue-process' on the process
> after stopping it for a while -- that's not possible if you delete the
> fd.  

Here "deleting" only removes the fd from the event loop; it doesn't
close the fd.  The fd can be added back by `continue-process'.

The patch below implements the basic idea.  Though, not very nicely
because in this case p->command can't be used to indicate that the fd is
temporarily "deleted".  It writes something to the process->plist.  A
proper patch would probably do this in a better way: