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Diffstat (limited to 'demo4/child.py')
-rw-r--r-- | demo4/child.py | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/demo4/child.py b/demo4/child.py new file mode 100644 index 0000000..f635769 --- /dev/null +++ b/demo4/child.py @@ -0,0 +1,23 @@ +import sysv_ipc +import time +import sys +import random + +# The parent passes the semaphore's name to me. +key = sys.argv[1] + +sem = sysv_ipc.Semaphore(int(key)) + +print('Child: waiting to aquire semaphore ' + key) + +with sem: + print('Child: semaphore {} aquired; holding for 3 seconds.'.format(sem.key)) + + # Flip a coin to determine whether or not to bail out of the context. + if random.randint(0, 1): + print("Child: raising ValueError to demonstrate unplanned context exit") + raise ValueError + + time.sleep(3) + + print('Child: gracefully exiting context (releasing the semaphore).') |