# This is a variant of the very old (early 90's) file
# Demo/threads/bug.py. It simply provokes a number of threads into
# trying to import the same module "at the same time".
# There are no pleasant failure modes -- most likely is that Python
# complains several times about module random having no attribute
# randrange, and then Python hangs.
from test
.test_support
import verbose
, TestSkipped
critical_section
= thread
.allocate_lock()
done
= thread
.allocate_lock()
global N
, critical_section
, done
x
= random
.randrange(1, 3)
critical_section
.acquire()
# Must release critical_section before releasing done, else the main
# thread can exit and set critical_section to None as part of global
# teardown; then critical_section.release() raises AttributeError.
critical_section
.release()
# Tricky: When regrtest imports this module, the thread running regrtest
# grabs the import lock and won't let go of it until this module returns.
# All other threads attempting an import hang for the duration. Since
# this test spawns threads that do little *but* import, we can't do that
# successfully until after this module finishes importing and regrtest
# regains control. To make this work, a special case was added to
# regrtest to invoke a module's "test_main" function (if any) after
def test_main(): # magic name! see above
# This triggers on, e.g., from test import autotest.
raise TestSkipped("can't run when import lock is held")
print "Trying", N
, "threads ...",
thread
.start_new_thread(task
, ())
if __name__
== "__main__":