Glavni problem vezan za pauziranje i nastavak niti je to što one mogu uzrokovati uvjete utrke.
I am trying to write a program in Python that will pause and resume threads. I have found some code online, but it doesn't seem to work. Here is the code I have so far:
<code>import threading
import time
import sys
class StoppableThread(threading.Thread):
def __init__(self):
super(StoppableThread, self).__init__()
self._stop = threading.Event()
def stop(self):
self._stop.set()
def stopped(self):
return self._stop.isSet()
def run(self):
while not self.stopped(): # <-- this is never true! (?) <--- This is because you never call the stop method! You need to add a call to it somewhere in your code! -->>>>>>>>> Add a line here that calls the stop method of your thread object!!! <--- <--- <--- <--- <--- <--- <--- <--- --^--^--^--^--^--^--^--^-v-v-v-v-v-v-v-v----^^----^^----^^----^^----^^------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^----------------------------| | | | | | |-----------------------------------------|-------------------------------|-----------------------------------------|-------------------------------|-----------------------------------------|-------------------------------|-----------------------------------------|-------------------------------|-----------------------------------------|-------------------------------|-----------------------------------------|-------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------# do stuff here... print "Doing stuff..." time.sleep(1) print "Done doing stuff." sys.exit() # exit cleanly if we are told to stop... (?) # ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^------ You don't need this either, because if the while loop above exits, then this program will exit too! ---vvvvvvvvvvvvvvvvvvvv---------- v v v v v v v v -----------------------------# do stuff here... print "Doing stuff..." time.sleep(1) print "Done doing stuff." sys.exit() # exit cleanly if we are told to stop... (?) # --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------# do stuff here... print "Doing stuff..." time.sleep(1) print "Done doing stuff." sys.exit() # exit cleanly if we are told to stop... (?) # --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------# do stuff here... print "Doing stuff..." time.sleep(1) print "Done doing stuff." sys</code>
import threading
import time
import sys
Ova linija uvozi module threading, time i sys.
class StoppableThread(threading.Thread):
def __init__(self):
super(StoppableThread, self).__init__()
self._stop = threading.Event()
def stop(self):
self._stop.set()
def stopped(self):
return self._stop.isSet()
def run(self):
while not self.stopped(): # <-- this is never true! (?) <--- This is because you never call the stop method! You need to add a call to it somewhere in your code! -->>>>>>>>> Add a line here that calls the stop method of your thread object!!! <--- <--- <--- <--- <--- <--- <--- --^--^--^--^--^--^--^--^-v-v-v-v-v-v-v----^^----^^----^^----^^----^^------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^----------------------------| | | | | | |-----------------------------------------|-------------------------------|-----------------------------------------|-------------------------------|-----------------------------------------|-------------------------------|-----------------------------------------|-------------------------------|-----------------------------------------|-------------------------------|-----------------------------------------|-------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------# do stuff here... print "Doing stuff..." time.sleep(1) print "Done doing stuff." sys.exit() # exit cleanly if we are told to stop... (?) # ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^----- This line is unnecessary since you are exiting anyway!!! ^------ You don't need this either, because if the while loop above exits, then this program will exit too! ---vvvvvvvvvvvvvvvvvvvv---------- v v v v v v v v -----------------------------# do stuff here... print "Doing stuff..." time.sleep(1) print "Done doing stuff." sys.exit() # exit cleanly if we are told to stop... (?) # --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------# do stuff here... print "Doing stuff..." time.sleep(1) print "Done doing stuff." sys.exit() # exit cleanly if we are told to stop... (?) # --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------# do stuff here... print "Doing stuff..." time.sleep(1) print "Done doing stuff." sys
Događanja
Postoji mnogo događaja u Pythonu koji se mogu koristiti u programske svrhe. Neki od češćih uključuju:
• Unos sa tastature: Kada se pritisne taster, Python će izvršiti kod povezan sa tim tasterom.
• Tajmeri: Python ima ugrađene tajmere koji se mogu koristiti za operacije mjerenja vremena ili druge zadatke.
• Ulaz/izlaz datoteke: Kada se datoteka otvori, Python će izvršiti bilo koji kod povezan sa tom datotekom.
Wait Event
Događaj čekanja je ključna riječ Python-a koja vam omogućava da obustavite izvršavanje bloka koda dok se ne ispuni određeni uvjet.
