1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
|
# Test that locks work when cancelling multiple waiters on the lock
try:
import asyncio
except ImportError:
print("SKIP")
raise SystemExit
async def task(i, lock, lock_flag):
print("task", i, "start")
try:
await lock.acquire()
except asyncio.CancelledError:
print("task", i, "cancel")
return
print("task", i, "lock_flag", lock_flag[0])
lock_flag[0] = True
await asyncio.sleep(0)
lock.release()
lock_flag[0] = False
print("task", i, "done")
async def main():
# Create a lock and acquire it so the tasks below must wait
lock = asyncio.Lock()
await lock.acquire()
lock_flag = [True]
# Create 4 tasks and let them all run
t0 = asyncio.create_task(task(0, lock, lock_flag))
t1 = asyncio.create_task(task(1, lock, lock_flag))
t2 = asyncio.create_task(task(2, lock, lock_flag))
t3 = asyncio.create_task(task(3, lock, lock_flag))
await asyncio.sleep(0)
# Cancel 2 of the tasks (which are waiting on the lock) and release the lock
t1.cancel()
t2.cancel()
lock.release()
lock_flag[0] = False
# Let the tasks run to completion
for _ in range(4):
await asyncio.sleep(0)
# The locke should be unlocked
print(lock.locked())
asyncio.run(main())
|
