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Re: about async process
From: |
Eli Zaretskii |
Subject: |
Re: about async process |
Date: |
Sat, 25 Aug 2018 21:39:53 +0300 |
> From: akrl <akrl@sdf.org>
> Date: Sat, 25 Aug 2018 18:15:50 +0000
>
> the question is: when is the process buffer updated after an async
> process finish to execute?
When Emacs is idle. From the ELisp manual:
Output from a subprocess can arrive only while Emacs is waiting: when
reading terminal input (see the function ‘waiting-for-user-input-p’), in
‘sit-for’ and ‘sleep-for’ (*note Waiting::), and in
‘accept-process-output’ (*note Accepting Output::). This minimizes the
problem of timing errors that usually plague parallel programming. For
example, you can safely create a process and only then specify its
buffer or filter function; no output can arrive before you finish, if
the code in between does not call any primitive that waits.
> (make-thread (lambda ()
> (let ((prc
> (start-process-shell-command "test"
> "out-buff"
> "echo foo")))
> (while (not (equal (process-status prc)
> 'exit))
> (thread-yield))
> (with-current-buffer "out-buff"
> (print (buffer-string))
> (sleep-for 0.1)
> (print (buffer-string))))))
>
> I'm trying to execut an async process in a thread yielding till this has
> finished and then reading the output.
> When I execute this code the first print is printing "" and just the
> second print after the sleep il latching the output I would expect.
> So my question is when is the output buffer updated and if ther's a way to
> ensure this has happend or to request for it?
With this code, the first instance of Emacs becoming idle is when you
call sleep-for. Calls to thread-yield don't count as idling.
- about async process, akrl, 2018/08/25
- Re: about async process,
Eli Zaretskii <=
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