Using time.sleep() in 2 threads causes lockup when hyper-threading is enabled

Below are 2 files that isolate the problem. Note, both programs hang
(stop responding) with hyper-threading turned on (a BIOS setting), but
work as expected with hyper-threading turned off.

Below are 2 files that isolate the problem. Note, both programs hang
(stop responding)
What does "stop responding" mean?
with hyper-threading turned on (a BIOS setting), but
work as expected with hyper-threading turned off.

Note, the Windows task manager shows 2 CPUs on the Performance tab with
hyper-threading is turned on.

Both Python 2.3.5 and 2.4.3 (downloaded from python.org) have this
problem.
The operating system is MS Windows XP Professional.

winmsd.exe shows:
2CPUs: x86 Family 15 Model 4 Stepping 1 GenuineIntel ~3000 MHz
Version: 5.1.2600 Service Pack 2 Build 2600

Could someone with a hyper-threading (or dual/multicore) CPU please
confirm this bug?
I don't see anything unexpected (to me) on a WinXP Pro SP2 box with HT
enabled, using 2.4.3, but I'm not sure what "not responding" means to
you.
# testsleep.py
import threading
import time

class Task(threading. Thread):
def __init__(self, n, t):
threading.Threa d.__init__(self )
self.n = n
self.t = t
def run(self):
print 'thread %d started' % self.n
print 'sleep time:', self.t
print time.clock()
print time.clock()
print time.clock()
print
count = 0
printCount = int(10 / self.t)
while True:
start = time.clock()
time.sleep(self .t)
stop = time.clock()
if stop - start > 1.0:
print 'thread', self.n, stop - start
You don't _expect_ this print to execute, do you? It should trigger
very rarely (if ever).
count += 1
if count > printCount:
count = 0
print self.n,

def test():
thread1 = Task(1, 0.01)
thread2 = Task(2, 0.003)
thread1.start()
thread2.start()

test()
This is what happened when I ran it, until I got tired of watching it
and killed the job:

C:\Python24>pyt hon test1.py
thread 1 started
sleep time: 0.01
7.8499538238e-007
4.42770924877e-005
8.62618455186e-005

thread 2 started
sleep time: 0.003
0.0004793495332 38
0.0005219042829 16
0.0005636490373 59

1 2 1 2 1 2 1 2 1 1 2 1 2 1 2 1 2 1 2 1 1 2 1 2 1
2 1 2 1 2 1 1 2 1 2 1 2 1 2 1 1 2 1 2 1 2 1 2 1 2
1 1 2 1 2 1 2 1 2 1 2 1 1 2 1 2 1 2 1 2 1
# testsleep2.py
import thread
import time
import sys

def run(n, t):
print 'thread %d started' % n
print 'sleep time:', t
print time.clock()
print time.clock()
print time.clock()
print
count = 0
printCount = int(10 / t)
while True:
start = time.clock()
time.sleep(t)
stop = time.clock()
if stop - start > 1.0:
print 'thread', n, stop - start
See above.
count += 1
if count > printCount:
count = 0
print n,

def test():
thread.start_ne w_thread(run, (1, 0.01))
thread.start_ne w_thread(run, (2, 0.003))

# Wait until the user presses the enter key.
sys.stdin.read( 1)
Do you want someone running this test to hit the ENTER key, or not?

test()

1 2 1 2 1 2 1 2 1 1 2 1 2 1 2 1 2 1 2 1 1 2 1 2 1
2 1 2 1 2 1 1 2 1 2 1 2 1 2 1 1 2 1 2 1 2 1 2 1 2
1 1 2 1 2 1 2 1 2 1 2 1 1 2 1 2 1 2 1 2 1

Do you want someone running this test to hit the ENTER key, or not?

What do you mean "stop responding"?

Both threads print their thread numbers (either 1 or 2) approximately
every 10 seconds. However, after a while (minutes to hours) both
programs (see above) hang!

Pressing ctrl-c (after the printing stops) causes the threads to "wake
up" from their sleep statement. And since the sleep took more than 1
seconds the thread number and the duration of the sleep is printed to
the screen.

Do you have a hyper-threading/dual/multi core CPU? Did you try this?

I got bored and tried to stop it with ctrl-c ...

Both threads print their thread numbers (either 1 or 2) approximately
every 10 seconds. However, after a while (minutes to hours) both
programs (see above) hang!
Where "hang" means they stop printing.
Pressing ctrl-c (after the printing stops) causes the threads to "wake
up" from their sleep statement. And since the sleep took more than 1
seconds the thread number and the duration of the sleep is printed to
the screen.

Do you have a hyper-threading/dual/multi core CPU? Did you try this?

I didn't run it for hours ;-)
Please try.

The sleep statement does not return! And this should not happen. The
code above does nothing special or unusual. The problem only occurs if
2 threads use the sleep statement and hyper-threading is enabled.

We discovered this bug perhaps a year ago. The only solution was to
tell our customers to disable hyper-threading (you can imagine they did
not like our "solution" very much). It then took many days of hard
work to isolate the problem down to the code I posted above.
Where "hang" means they stop printing.