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bug#19494: 25.0.50; infinite loop in readable_event on master branch
From: |
Noah Friedman |
Subject: |
bug#19494: 25.0.50; infinite loop in readable_event on master branch |
Date: |
Fri, 02 Jan 2015 19:18:03 -0800 (PST) |
Ever since commit 614beeecf29d16c08f66a4f82b6085be90df8a74 (c. Nov 01 2014)
I keep finding "idle" emacs processes running in a tight loop in
keyboard.c:readable_event after I come back to my session the following
morning. In those cases, kbd_buffer is full of the same event, in my case:
$17 = {
kind = BUFFER_SWITCH_EVENT,
part = scroll_bar_nowhere,
code = 0,
modifiers = 0,
x = 0,
y = 0,
timestamp = 0,
frame_or_window = 12962290,
arg = 12962290
}
That is, the entire kbd_buffer queue is BUFFER_SWITCH_EVENT events.
Because of that, it means the sequence
do {
....
if (event == kbd_buffer + KBD_BUFFER_SIZE)
event = kbd_buffer;
}
while (event != kbd_store_ptr);
in the function readable_event will, at least at times, loop forever.
I don't have a trivial or always-reliable test case but I think the
offending elisp is the following, running in a (non-idle) timer:
(force-mode-line-update 'all)
(sit-for 0) ; force redisplay
I can change the elisp in question since I wrote it, but I'm not sure what
the right way to do it is since it's not just running during idle times.
In any case having emacs lock up in a non-recoverable way seems like a bug,
since the only way out is to hit C-g and abort, or else go in with gdb
on the running process and force a return.
Maybe this loop needs some kind of "didn't find any other event" flag to
avoid looping, but I thought I'd check with the original committer first in
case he has a better idea.
- bug#19494: 25.0.50; infinite loop in readable_event on master branch,
Noah Friedman <=