Date: Mon, 20 Aug 2018 11:53:03 -0700 From: John-Mark Gurney <jmg@funkthat.com> To: Ian Lepore <ian@freebsd.org>, freebsd-arm@FreeBSD.org Cc: manu@FreeBSD.org Subject: Re: sx_sleep not waking up when timo expires Message-ID: <20180820185303.GH97145@funkthat.com> In-Reply-To: <20180811020136.GD97145@funkthat.com> References: <20180729010157.GC2884@funkthat.com> <1532874944.61594.110.camel@freebsd.org> <20180811020136.GD97145@funkthat.com>
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John-Mark Gurney wrote this message on Fri, Aug 10, 2018 at 19:01 -0700:
> Also, I've had the shell command sleep hang as well.. I figure that's
> expected, but made me realized that a good test program could be to
> fire up a bunch of threads and sleep in them, to make finding the
> problem more quickly....
>
> Anything I can do to help debug/fix it?
>
> I have a couple spare LTS boards specifically to do stuff like this.
I wrote a program to trigger the issue. It triggered the issue in only
an hour or two on both the A64-LTS boards that I've tried it on.
Hopefully this can help others debug it.
On my firewall board, that does a lot of interrupts, it happens a lot more
frequently. In the last 4 hours or so of running the program, I've had 6
threads hang in sleep.
# vmstat -i
interrupt total rate
gic0,p11: + 664239597 676
gic0,s0: uart0 10659 0
gic0,s60: aw_mmc0 70294 0
gic0,s82: awg0 452027133 460
cpu0:ast 511 0
cpu1:ast 48 0
cpu2:ast 34 0
cpu3:ast 35 0
cpu0:preempt 15682717 16
cpu1:preempt 14384242 15
cpu2:preempt 16722306 17
cpu3:preempt 16798837 17
cpu0:rendezvous 300161 0
cpu1:rendezvous 8545 0
cpu2:rendezvous 300183 0
cpu3:rendezvous 300115 0
cpu0:hardclock 35093 0
Total 1180880510 1201
# uptime
11:50AM up 11 days, 9:03, 8 users, load averages: 0.68, 0.83, 0.93
The other box that has only two threads freeze has a total rate of 77..
---- sleeptest.py ----
import Queue
import threading
import time
import random
def sleepfun(q, lngth, extlst, idobj):
while not extlst:
#factor = (random.random() + 1) * 4
factor = 1
factor = (random.random() * .5 + 1)
time.sleep(lngth * factor)
q.put((idobj, time.time()))
def run():
sleeplength = .5
exitlist = []
nthreads = 20
q = Queue.Queue()
thds = {}
lastcheck = {}
for i in xrange(nthreads):
obj = object()
thr = threading.Thread(target=sleepfun, args=(q, sleeplength, exitlist, obj))
thds[obj] = thr
lastcheck[obj] = time.time()
thr.start()
try:
while True:
for i in xrange(nthreads*3):
obj, tm = q.get()
lastcheck[obj] = tm
cur = time.time()
for i in lastcheck.keys():
if not thds[i].isAlive():
print 'thread died.'
del thds[i]
del lastcheck[i]
continue
print 'last checkin:', cur - lastcheck[i]
if cur - lastcheck[i] > 2 * sleeplength:
print 'thread is stuck:', `obj`, 'since:', time.ctime(lastcheck[i])
except KeyboardInterrupt:
print 'trying to exit...'
print time.ctime(time.time())
exitlist.append(True)
for i in thds:
thds[i].join()
if __name__ == '__main__':
run()
---- sleeptest.py ----
--
John-Mark Gurney Voice: +1 415 225 5579
"All that I will do, has been done, All that I have, has not."
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