From: John Wiegley <johnw@newartisans.com>
To: eliz@gnu.org
Cc: 30322@debbugs.gnu.org
Subject: bug#30322: Emacs 26 seems to have entered an infinite loop during GC on macOS
Date: Thu, 01 Feb 2018 12:09:59 -0800 [thread overview]
Message-ID: <1517515799.3889240.1256382320.18166E1D@webmail.messagingengine.com> (raw)
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Hi Eli,
I was writing an e-mail to a colleague today when my Emacs window completely froze up, taking 100% CPU constantly. Since it's still in that state now, I decided to fire up the stochastic profiler to see what it's doing. I've attached the screenshot.
It claims to be spending all its time in `lisp_align_free', behaving as if there's a CPU busy loop now taking place inside that function. Since very little time is being assigned to its callees, I believe an infinite loop has occurred here:
int i = 0;
bool aligned = busy;
struct ablock **tem = &free_ablock;
struct ablock *atop = &abase->blocks[aligned ? ABLOCKS_SIZE : ABLOCKS_SIZE - 1];
while (*tem)
{
if (*tem >= (struct ablock *) abase && *tem < atop)
{
i++;
*tem = (*tem)->x.next_free;
}
else
tem = &(*tem)->x.next_free;
}
I would like to suggest that before entering this loop, we record the initial value of *tem, and if we encounter again (or if we encounter it again X number of times), we report a non-fatal error and exit this function. That way I could save my work and restart Emacs.
I've noticed such a "lock up until I force quit" happening before, but it's very rare. Maybe a few times a year?
John
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next reply other threads:[~2018-02-01 20:09 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-01 20:09 John Wiegley [this message]
2019-10-09 21:33 ` bug#30322: Emacs 26 seems to have entered an infinite loop during GC on macOS Lars Ingebrigtsen
2020-08-16 16:49 ` Lars Ingebrigtsen
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