Python: threads differently
Introduction
Do you know why I decided to write this article? I wrote a program where I used threads. While working with them Python more and more you convince yourself that everything is bad with them. No, it’s not that they don’t work well. Just using them, to put it mildly, is inconvenient. I decided to write a simple but more convenient library, and I’ll share the process here.
PS: At the end I will leave a link to GitHub
The first steps
The first thing I decided to start with is the convenient creation of threads from functions. To do this, I wrote a simple decorator, it looks like this:
# thr.py
from threading import Thread as thrd
__all__ = ['Thr']
# Класс для всего содержимого либы
class Thr:
# Собственно, декоратор
def thread(fn):
def thr(*args, **kwargs):
thrd(target = fn, args = (*args,), kwargs={**kwargs,}).start()
pass
return thr
pass
# конец файлаThat’s all. Now you can create streams very conveniently:
from thr import Thr
# пример использования
@Thr.thread
def func1(a, b, c):
if a+b > c:
if a+c > b:
if b+c > a:
print("треугольник существует")
pass
pass
pass
print("треугольник не существует")
pass # возвращение значений пока не предусмотрено
for a, b, c in zip(range(1, 10), range(6, 15), range(11, 20)):
func1(a, b, c)
passMore convenient than before, right? But I didn’t get enough.
Thread Environments
It became not convenient for me to ensure the correct interaction of threads. For example, I need 2 loops to solve sequences of numbers for 3n+1. Then I had to suffer Python global variables. And I found a way!
PS: Maybe it is ThreadPoolExecutorwhich I have never used. If so, then perhaps my method will simply seem more convenient to someone.
Let’s explain. You create an environment for threads (multiple possible) and Little adapt streaming functions for yourself. library code:
# thr.py
from curses.ascii import isalnum
from threading import Thread as thrd
from random import randrange
from sys import exit as exitall
__all__ = ['Thr']
# f-str не позволяет использовать "\" напрямую,
# пришлось выкручиваться =)
nl = "\n"
bs = "\b"
tb = "\t"
rt = "\r"
# просто полезная функция
def strcleanup(s: str = ""):
while s[0] == ' ': s = s[1:]
while s[-1] == ' ': s = s[:-1]
if not isalnum(s[0]): s="_" + s
s = s.replace(' ', '_')
for i in range(len(s)):
if not isalnum(s[i]):
s = s.replace(s[i], '_')
pass
pass
s += f"{randrange(100, 999)}"
return s
# Класс для всего содержимого либы
class Thr:
# класс для сред потоков
class Env(object):
# поля
# потоки
thrs: list = None
# возвращаемые значения
rets: dict = None
# название среды
name: str = None
# методы
# инициализация
def __init__(self, name):
self.thrs = []
self.rets = {}
self.__name__ = self.name = name
# self.name на всякий случай.
# __name__ - магическая переменная, вдруг поменяется.
pass
# в строку
__str__ = lambda self:\
f"""ThreadSpace "{self.name}": {len(self.thrs)} threads"""
# тоже в строку, но скорее для дебага, чем для печати юзеру
__repr__ = lambda self:\
f"""ThreadSpace "{self.name}"
threads:
{(nl+" ").join(self.thrs)}
total: {len(self.thrs)}
"""
def __add__(self, other):
self.thrs = {**self.thrs, **other.thrs}
pass
# Декоратор/метод для добавления в список потоков.
def append(self, fn):
# функции нужен docstring
ID = strcleanup(fn.__doc__.casefold())
self.thrs += [ID]
self.rets[ID] = None
#
class Thrd(object):
ID = None
space = None
fn = None
thr = None
runned = None
ret = None
def __init__(slf, ID, self, fn):
slf.ID = ID
slf.space = self
slf.fn = fn
slf.thr = None
slf.runned = False
slf.ret = False
pass
def run(slf, *args):
if slf.runned:
print(f"Exception: Thread \"{slf.ID[:-3]}\" of threadspace \"{slf.space.name}\" already started")
exitall(1)
pass
slf.thr = thrd(target = slf.fn, args = (slf, slf.space, slf.ID, *args,))
slf.thr.start()
slf.runned = True
pass
def join(slf):
if not slf.runned:
print(f"Exception: Thread \"{slf.ID[:-3]}\" of threadspace \"{slf.space.name}\" not started yet")
exitall(1)
pass
slf.thr.join()
slf.runned = False
pass
def get(slf):
if not slf.ret:
print(f"Exception: Thread \"{slf.ID[:-3]}\" of threadspace \"{slf.space.name}\" didn`t return anything yet")
exitall(1)
pass
slf.runned = False
return slf.space.rets[slf.ID]
def getrun(slf, *args):
slf.run(*args)
slf.join()
return slf.get()
pass
return Thrd(ID, self, fn)
pass
# Декоратор для "голого" потока
def thread(fn):
def thr(*args, **kwargs):
thrd(target = fn, args = (*args,), kwargs={**kwargs,}).start()
pass
return thr
pass
# конец файлаAn example of an error output:
Traceback (most recent call last):
File "test.py", line 37, in <module>
loop.run()
File "thr.py", line 93, in run
raise Exception(...)
Exception: Thread "3n_1_mainloop" of threadspace "3n+1" already startedHow quickly the amount of code has grown compared to the previous version! So, an example of usage:
from random import randint
from thr import Thr
Space = Thr.Env("3n+1")
@Space.append
def hdl(t, spc, ID, num):
"""3n+1_handle"""
if num % 2 == 0:
# значения возвращать так
t.ret = True
spc.rets[ID] = num/2
return
# значения возвращать так
t.ret = True
spc.rets[ID] = 3*num+1
return
@Space.append
def loop(t, spc, ID, num):
"""3n+1_mainloop"""
steps = 0
while num not in (4, 2, 1):
num = hdl.getrun(num)
steps += 1
pass
# значения возвращать так
t.ret = True
spc.rets[ID] = steps
return
print()
print(Space)
print()
print(repr(Space))
ticks = 0
num = randint(5, 100)
loop.run(num)
while not loop.ret:
ticks += 1
pass
print(f"loop reached 4 -> 2 -> 1 trap,\n"
f"time has passed (loop ticks):\n"
f"{ticks}, steps has passed: {loop.get()}, start number: {num}")Conclusion:
ThreadSpace "3n+1": 2 threads
ThreadSpace "3n+1"
threads:
3n_1_handle840
3n_1_mainloop515
total: 2
loop reached 4 -> 2 -> 1 trap,
time has passed (loop ticks):
13606839, steps has passed: 33, start number: 78So, this is where I will end this article. Thank you for your attention!
