"python@thread" semaphore& Candy Machine

The signal volume is applicable to multi-threaded competition with limited resources.

1  fromAtexitImportRegister2  fromTimeImportctime, Sleep3  fromThreadingImportThread, Lock, Boundedsemaphore4  fromRandomImportRandrange5 6Lock =Lock ()7MAX = 5#Semaphore size8Candytray =Boundedsemaphore (MAX)9 Ten  one defrefull (): a with lock: -         Print('refulling ...') -         Try: the candytray.release () -         exceptvalueerror: -             Print('is full!') -         Else: +             Print('OK') -  + defbuy (): a with lock: at         Print('Buying ...') -         ifCandytray.acquire (False):#Add false parameter, if semaphore is empty, then do not block, but return error, feel similar to Pthread_mutex_trylock in C language -             Print('OK') -         Else: -             Print('Empty') -  in defConsumer (loops): -      forIinchRange (loops): to refull () +Sleep (randrange (3))#the probability of sleeping longer than creater is as large as possible, -  the  * defcreater (loops): $      forIinchRange (loops):Panax Notoginseng buy () -Sleep (randrange (5)) the  +  a defMain (): the     Print('starting ...') +n = Randrange (2,6) -     Print('the Candy Mechine full with {0}'. Format (MAX)) $Thread (target=creater,args= (randrange (n,n+max+2)) . Start () $Thread (target=consumer, args= (randrange (n,n+max+2)) . Start () -  -  the @register - defAtexitt ():Wuyi     Print('the end!') the  -  wu if __name__=='__main__': -Main ()

Output result:

Reference: Python core Programming-fourth Chapter Wesley Chun

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