03 flask源码剖析之threading.local和高级

03 threading.local和高级

1.python之threading.local

• 当每个线程在执行 val.num=1 ，在内部会为此线程开辟一个空间，来存储 num=1

• val.num,找到此线程自己的内存地址去取自己存储 num

  import time
  import threading
  
  val1 = threading.local()
  
  def task(i):
      val.num = i
      time.sleep(1)
      print(val.num)
  
  for i in range(4):
      t = threading.Thread(target=task,args=(i,))
      t.start()

2. 线程唯一标识

• get_ident

  import threading
  from threading import get_ident
  
  def task():
      ident = get_ident()
      print(ident)
  for i in range(20):
      t = threading.Thread(target=task)
      t.start()

3. 自定义threading.local

• 储存结构：

  storage = {
  1112:{‘x1‘:1}
  1113:{‘x1‘:2}
  1114:{‘x1‘:3}
  1115:{‘x1‘:4}
  }

  import threading
  class Local(object):
      def __init__(self):
          object.__setattr__(self,'storage',{})
  
      def __setattr__(self, key, value):
          ident = threading.get_ident()
          if ident in self.storage:
              self.storage[ident][key] = value
          else:
              self.storage[ident] = {key:value}
  
      def __getattr__(self, item):
          ident = threading.get_ident()
          if ident not in self.storage:
              return
          return self.storage[ident].get(item)
  
  local = Local()
  
  def task(arg):
      local.x1 = arg
      print(local.x1)
  
  for i in range(5):
      t = threading.Thread(target=task,args=(i,))
      t.start()

4. 加强版threading.local

• 储存结构：

  storage = {
  1111:{‘x1‘:[]},
  1112:{‘x1‘:[]}
  1113:{‘x1‘:[]}
  1114:{‘x1‘:[]}
  1115:{‘x1‘:[]},
  1116:{‘x1‘:[]}
  }

  import threading
  class Local(object):
      def __init__(self):
          object.__setattr__(self,'storage',{})
  
      def __setattr__(self, key, value):
          ident = threading.get_ident()
          if ident in self.storage:
              self.storage[ident][key].append(value)
          else:
              self.storage[ident] = {key:[value,]}
  
      def __getattr__(self, item):
          ident = threading.get_ident()
          if ident not in self.storage:
              return
          return self.storage[ident][item][-1]
  
  local = Local()
  
  def task(arg):
      local.x1 = arg
      print(local.x1)
  
  for i in range(5):
      t = threading.Thread(target=task,args=(i,))
      t.start()

03 flask源码剖析之threading.local和高级

原文：https://www.cnblogs.com/liubing8/p/11930170.html