Um, nevermind :) I finally was able to reproduce the problem in the lab
and, well, it was my fault. It was a very occasional memory stomp. Sorry
for the noise.
Ken
On Fri, 10 Aug 2007 14:07:59 -0400, Ken Cox <[EMAIL PROTECTED]> wrote:
I have a libevent program that wakes up every 20ms and does some
processing. For this I use one event and repeatedly call event_add
reusing the same event. In the field I see occasional crashes in
event_tree_RB_INSERT or event_tree_RB_INSERT_COLOR, but I can't
reproduce them in the lab or under valgrind.
If you have seen this kind of crash, or can tell I'm doing something
dreadfully wrong, or just can give me a general clue, I would greatly
appreciate it.
I built on r309 from the SVN trunk.
Here's one such stack.
Program terminated with signal 11, Segmentation fault.
#0 compare (a=0x8648924, b=0x1) at event.c:136
136 event.c: No such file or directory.
in event.c
(gdb) bt
#0 compare (a=0x8648924, b=0x1) at event.c:136
#1 0x08063bcd in event_tree_RB_INSERT (head=0x86481cc, elm=0x8648924)
at event.c:170
#2 0x0806406e in event_queue_insert (base=0x86481a0, ev=0x8648924,
queue=1) at event.c:847
#3 0x0806429e in event_add (ev=0x8648924, tv=0x86489d4) at event.c:635
#4 0x08055062 in process_cb (fd=-1, what=1, arg=0x86488b0) at foo.c:335
#5 0x080649a4 in event_base_loop (base=0x86481a0, flags=0) at
event.c:313
#6 0x08064b4a in event_loop (flags=0) at event.c:364
#7 0x08064b62 in event_dispatch () at event.c:327
#8 0x08057d42 in main (argc=3, argv=0xbf985764) at foo.c:1061
The code looks kind of like this:
struct event timer_ev;
struct timeval next_wakeup_tv, snooze_tv;
void process_once(void *arg)
{
}
/* timer callback, invokes process_once and sets next timer */
void process_cb(int fd, short what, void *arg)
{
struct timeval now, then;
struct timeval delta_tv = {0, 20000};
process_once(arg);
/* calculate next wakeup time */
timeradd(&next_wakeup_tv, &delta_tv, &then);
next_wakeup_tv = then;
/* calculate snooze time until then; don't allow it to go negative */
gettimeofday(&now, NULL);
if (timercmp(&then, &now, <))
timerclear(&snooze_tv);
else
timersub(&then, &now, &snooze_tv); /* snooze = then - now */
event_add(&timer_ev, &snooze_tv);
fprintf(stderr, "%s: snooze={%lu, %6lu} next={%lu, %6lu}\n", __func__,
snooze_tv.tv_sec, snooze_tv.tv_usec,
next_wakeup_tv.tv_sec, next_wakeup_tv.tv_usec);
}
/* bootstrap timer */
void start(void *arg)
{
struct timeval now, delta_tv = {0, 20000};
event_set(&timer_ev, -1, 0, process_cb, arg);
event_add(&timer_ev, &delta_tv);
gettimeofday(&now, NULL);
timeradd(&now, &delta_tv, &next_wakeup_tv);
}
==
Ken
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--
-Ken
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