cpython/Lib/test/test_thread.py

# Very rudimentary test of thread module

# Create a bunch of threads, let each do some work, wait until all are done

from test.test_support import verbose
import random
import thread
import time

mutex = thread.allocate_lock()
rmutex = thread.allocate_lock() # for calls to random
running = 0
done = thread.allocate_lock()
done.acquire()

numtasks = 10

def task(ident):
    global running
    rmutex.acquire()
    delay = random.random() * numtasks
    rmutex.release()
    if verbose:
        print('task', ident, 'will run for', round(delay, 1), 'sec')
    time.sleep(delay)
    if verbose:
        print('task', ident, 'done')
    mutex.acquire()
    running = running - 1
    if running == 0:
        done.release()
    mutex.release()

next_ident = 0
def newtask():
    global next_ident, running
    mutex.acquire()
    next_ident = next_ident + 1
    if verbose:
        print('creating task', next_ident)
    thread.start_new_thread(task, (next_ident,))
    running = running + 1
    mutex.release()

for i in range(numtasks):
    newtask()

print('waiting for all tasks to complete')
done.acquire()
print('all tasks done')

class barrier:
    def __init__(self, n):
        self.n = n
        self.waiting = 0
        self.checkin  = thread.allocate_lock()
        self.checkout = thread.allocate_lock()
        self.checkout.acquire()

    def enter(self):
        checkin, checkout = self.checkin, self.checkout

        checkin.acquire()
        self.waiting = self.waiting + 1
        if self.waiting == self.n:
            self.waiting = self.n - 1
            checkout.release()
            return
        checkin.release()

        checkout.acquire()
        self.waiting = self.waiting - 1
        if self.waiting == 0:
            checkin.release()
            return
        checkout.release()

numtrips = 3
def task2(ident):
    global running
    for i in range(numtrips):
        if ident == 0:
            # give it a good chance to enter the next
            # barrier before the others are all out
            # of the current one
            delay = 0.001
        else:
            rmutex.acquire()
            delay = random.random() * numtasks
            rmutex.release()
        if verbose:
            print('task', ident, 'will run for', round(delay, 1), 'sec')
        time.sleep(delay)
        if verbose:
            print('task', ident, 'entering barrier', i)
        bar.enter()
        if verbose:
            print('task', ident, 'leaving barrier', i)
    mutex.acquire()
    running -= 1
    # Must release mutex before releasing done, else the main thread can
    # exit and set mutex to None as part of global teardown; then
    # mutex.release() raises AttributeError.
    finished = running == 0
    mutex.release()
    if finished:
        done.release()

print('\n*** Barrier Test ***')
if done.acquire(0):
    raise ValueError("'done' should have remained acquired")
bar = barrier(numtasks)
running = numtasks
for i in range(numtasks):
    thread.start_new_thread(task2, (i,))
done.acquire()
print('all tasks done')

# not all platforms support changing thread stack size
print('\n*** Changing thread stack size ***')
if thread.stack_size() != 0:
    raise ValueError("initial stack_size not 0")

thread.stack_size(0)
if thread.stack_size() != 0:
    raise ValueError("stack_size not reset to default")

from os import name as os_name
if os_name in ("nt", "os2", "posix"):

    tss_supported = 1
    try:
        thread.stack_size(4096)
    except ValueError:
        print('caught expected ValueError setting stack_size(4096)')
    except thread.error:
        tss_supported = 0
        print('platform does not support changing thread stack size')

    if tss_supported:
        failed = lambda s, e: s != e
        fail_msg = "stack_size(%d) failed - should succeed"
        for tss in (262144, 0x100000, 0):
            thread.stack_size(tss)
            if failed(thread.stack_size(), tss):
                raise ValueError(fail_msg % tss)
            print('successfully set stack_size(%d)' % tss)

        for tss in (262144, 0x100000):
            print('trying stack_size = %d' % tss)
            next_ident = 0
            for i in range(numtasks):
                newtask()

            print('waiting for all tasks to complete')
            done.acquire()
            print('all tasks done')

        # reset stack size to default
        thread.stack_size(0)