import threading
import time
from werkzeug.local import Local, LocalStack
my_local = Local()
my_local.a = 'a'
my_stack = LocalStack()
my_stack.push(1)
print(my_stack.top)
def worker():
print('I am a thread worker')
print(my_stack.top)
t = threading.current_thread()
# time.sleep(10)
print(t.getName())
my_local.a = 'b'
print(my_local.a)
my_stack.push(2)
print(my_stack.top)
new_t1 = threading.Thread(target=worker, name='new thread1')
new_t1.start()
# new_t2 = threading.Thread(target=worker, name='new thread2')
# new_t2.start()
time.sleep(1)
t = threading.current_thread()
因为在flask中都是用同一个变量名去引用相似的一类对象，如request引用Request对象，如何正确区分？
flask通过包装成上下文对象，通过栈的特性，来保证上下文对象的存储和一致性（AppContext对象和RequestContext对象配套）。
线程隔离特性，保证线程之间操作各自的栈而互不干扰。（Request对象因为实例化了多个，所以需要隔离，而核心对象实际上只有一个，隔不隔离没有意义。）
意义在于：能使当前的线程能够正确引用到他自己所创建的对象，而不是引用到其他线程所创建的对象。虽然都叫相同的名字，但是从各自的栈顶取。从而保证不同请求的隔离性。
为什么要用一个栈来存取上下文对象？
实际上多线程模式下，一个请求由一个线程来处理，请求来进栈，处理完出栈，不需要保存多个上下文。但有些情况下，如离线脚本或单元测试时，可能会需要推入多个上下文，故需要一个容器来存取。
'''
import time
from threading import Thread, current_thread
from werkzeug.local import Local, LocalStack
obj = Local()
obj.a = 1
print(f'In {current_thread().name} {obj.__ident_func__()} obj.a is', obj.a)
def manipulate():
obj.a = 2
print(f'In {current_thread().name} {obj.__ident_func__()} obj.a is', obj.a)
newThread = Thread(name='newThread', target=manipulate)
newThread.start()
time.sleep(1)
print(f'In {current_thread().name} {obj.__ident_func__()} obj.a is', obj.a)
# 线程隔离栈的试验
# -*- coding: utf-8 -*-
# @Time : 2019/4/10 19:59
# @Author : Lwq
# @File : testthread2.py
# @Software: PyCharm
import threading
import time
from werkzeug.local import Local
'''
线程有隔离
'''
test = Local()
test.a = 1
def work():
test.a = 2
print('new thread' + str(test.a))
thread_1 = threading.Thread(target=work)
thread_1.start()
# 停留一秒是确保线程1执行完成
time.sleep(1)
print('main thread' + str(test.a))
import threading
import time
from werkzeug.local import Local
class A:
a = 10
def __str__(self):
return "A: <{}>".format(self.a)
# 主线程
my_obj = Local()
my_obj.a = 10
def worker():
my_obj.a = 20
print('in the new thread t1 is : {}'.format(my_obj.a))
print("in the workder, get_indent(): {}".format(threading.get_ident()))
t1 = threading.Thread(target=worker, name='t1_thread')
t1.start()
t1.join()
import threading
import time
from werkzeug.local import Local
my_obj = Local()
my_obj.a = 1
def worker():
my_obj.a = 2
print("new thread a is ", my_obj.a)
new_thread = threading.Thread(target=worker, name="new_thread")
new_thread.start()
time.sleep(2)
print("main thread a is", my_obj.a)
