Re: Timers and sentinels

[Uday S Reddy <u.s.reddy@cs.bham.ac.uk>]

On 9/25/2010 2:49 PM, Lars Magne Ingebrigtsen wrote:
> I'm trying to track down a bug that's pretty elusive.  I may be looking
> in the totally wrong place, but what seems to happen is that I have a
> function (run from a timer) that alters some part of the Gnus article
> buffer.  At the same time, there's an URL process filter/sentinel that's
> being run, and inserts images asynchronously into the buffer.
>
> Is it possible that the function that's being run from the timer is
> being interrupted by the process filter/sentinel function?  I had half
> imagined that all these "multi-threaded" functions were being run with,
> er, "interrupts off", so to speak.

Whenever the "main" Emacs thread does an accept-process-output or sit-for, 
timer tasks can run.  I was also bitten by this issue a few times.  It is 
important that the timer tasks be short and refrain from changing any important 
state that might affect the main thread.

The JUST-THIS-ONE argument of accept-process-output can be used to "turn off 
the interrupts", so to speak.

Cheers,
Uday