多线程或多进程

Question

所以，目前，我使用多处理来运行这3个函数在一起。

由于只有令牌更改，是否建议切换到多线程?(如果是的话，它真的会对性能有帮助吗?比如加速，我认为内存的使用肯定会减少)

这是我的代码:

from database_function import *
from kiteconnect import KiteTicker
import pandas as pd
from datetime import datetime, timedelta
import schedule
import time
from multiprocessing import Process

def tick_A():
#credentials code here
tokens = [x[0] for x in db_fetchquery("SELECT zerodha FROM script ORDER BY id ASC LIMIT 50")] #FETCHING FIRST 50 SCRIPTS TOKEN
#print(tokens)
##### TO MAKE SURE THE TASK STARTS AFTER 8:59 ONLY ###########
t = datetime.today()
future = datetime(t.year,t.month,t.day,8,59)
if ((future-t).total_seconds()) < 0:
future = datetime(t.year,t.month,t.day,t.hour,t.minute,(t.second+2))
time.sleep((future-t).total_seconds())
##### TO MAKE SURE THE TASK STARTS AFTER 8:59 ONLY ###########

def on_ticks(ws, ticks):
global ltp
ltp = ticks[0]["last_price"]
for tick in ticks:
print(f"{tick['instrument_token']}A")
db_runquery(f'UPDATE SCRIPT SET ltp = {tick["last_price"]} WHERE zerodha = {tick["instrument_token"]}') #UPDATING LTP IN DATABASE
#print(f"{tick['last_price']}")

def on_connect(ws, response):
#print(f"response from connect :: {response}")
# Subscribe to a list of instrument_tokens (TOKENS FETCHED ABOVE WILL BE SUBSCRIBED HERE).
# logging.debug("on connect: {}".format(response))
ws.subscribe(tokens)
ws.set_mode(ws.MODE_LTP,tokens) # SETTING TOKEN TO TICK MODE (LTP / FULL / QUOTE)
kws.on_ticks = on_ticks
kws.on_connect = on_connect
kws.connect(threaded=True)
#####TO STOP THE TASK AFTER 15:32 #######
end_time = datetime(t.year,t.month,t.day,15,32)
while True:
schedule.run_pending()
#time.sleep(1)
if datetime.now() > end_time:
break
#####TO STOP THE TASK AFTER 15:32 #######

def tick_B():
everything remains the same only tokens value changes
tokens = [x[0] for x in db_fetchquery("SELECT zerodha FROM script ORDER BY id ASC OFFSET (50) ROWS FETCH NEXT (50) ROWS ONLY")]

def tick_C():
everything remains the same only tokens value changes
tokens = [x[0] for x in db_fetchquery("SELECT zerodha FROM script ORDER BY id ASC OFFSET (100) ROWS FETCH NEXT (50) ROWS ONLY")]


if __name__ == '__main__':
def runInParallel(*fns):
proc = []
for fn in fns:
p = Process(target=fn)
p.start()
proc.append(p)
for p in proc:
p.join()
runInParallel(tick_A , tick_B , tick_C)

所以，目前，我使用多进程运行这三个函数在一起。

由于只有令牌更改，是否建议切换到多线程?(如果是的话，它真的会对性能有帮助吗?比如加速，我认为内存的使用肯定会减少)

Answer 1

大多数Python实现都没有真正的多线程，因为它们使用全局锁(GIL)。所以一次只运行一个线程。对于大量I/O应用程序，这应该没有什么区别。但是如果你需要并行完成CPU繁重的操作(我看到你使用Panda -所以答案一定是肯定的)-你最好还是使用多进程应用程序。