學習協程，原理看鏈接。只要能看懂這一個實例，基本上你就能夠運用greenlet編寫協程。

前提你對yield已經了解，佛則應先學yield.

1.原理

? ? ? ??https://www.cnblogs.com/Security-Darren/p/4167961.html

? ? ? ?https://www.oschina.net/question/3306142_2242565

2.1.yield消費者協程

2.2.greenlet消費者協程

3.yield使用說明

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2.1yield消費者協程

import time

def consumer():
??? send_data2 = ''
??? while True:
??????? receive_data2 = yield send_data2 #receive_data2接收數據；send_data2發送數據
??????????? #向函數發送值時函數會執行 通過 yield拿到消息，處理，又通過 yield把結果傳回；
??????? if not receive_data2:
??????????? return
??????? print('2.客戶:接收（生成數量）= %s ;' % receive_data2)
??????? time.sleep(1)
??????? send_data2 = '￥'+str(100*receive_data2)
??????? print('2.客戶：發送（付款金額）=%s ;' % send_data2)

def produce(c):
??? next(c)? #c.send(None)啟動生成器????????????????? #向前執行到第一條語句，準備接收
??? send_data1 = 0
??? while send_data1 < 3:
??????? send_data1 = send_data1 + 1
??????? print('1.工廠：發送（生產數量）= %s pcs ;' % send_data1)
??????? receive_data1 = c.send(send_data1 )#send_data1發送數據；receive_data1接受數據
??????? print('1.工廠：接收（客戶付款）=: %s ;' % receive_data1)
??? c.close() #produce決定不生產了，通過c.close()關閉 consumer，整個過程結束

#******************************************
if __name__=='__main__':
#??? 調用：
??? c = consumer()
??? produce(c)
?#-----------------------------------------------
#1.工廠：發送（生產數量）= 1 pcs ;
#2.客戶:接收（生成數量）= 1 ;
#2.客戶：發送（付款金額）=￥100 ;
#1.工廠：接收（客戶付款）=: ￥100 ;
#1.工廠：發送（生產數量）= 2 pcs ;
#2.客戶:接收（生成數量）= 2 ;
#2.客戶：發送（付款金額）=￥200 ;
#1.工廠：接收（客戶付款）=: ￥200 ;
#1.工廠：發送（生產數量）= 3 pcs ;
#2.客戶:接收（生成數量）= 3 ;
#2.客戶：發送（付款金額）=￥300 ;
#1.工廠：接收（客戶付款）=: ￥300 ;


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2.2.greenlet消費者協程
??? # 消費者協程
??? from greenlet import greenlet
???
??? def consumer():
??????? send_data2 = ''
??????? while True:
??????????? receive_data2 = pro.switch(send_data2)
??????????? if receive_data2? is not None:
??????????????? print( '2.receive_data2= %s' % receive_data2 )
??????????????? send_data2 = receive_data2 *10+1
??????????????? print('2.send_data2=',send_data2)
?????
??? def producer(n):
??????? con.switch()
??????? i = 0
??????? while i < n:
??????????? i += 1
??????????? print( '1.send_data1= %s' % i)
??????????? receive_data1 = con.switch(i)
??????????? print('1.receive_data1=',receive_data1)
?????
??? pro = greenlet(producer)
??? con = greenlet(consumer)
??? pro.switch(5)
??? ??
??? # 1.send_data1= 1
??? # 2.receive_data2= 1
??? # 2.send_data2= 11
??? # 1.receive_data1= 11
??? # 1.send_data1= 2
??? # 2.receive_data2= 2
??? # 2.send_data2= 21
??? # 1.receive_data1= 21
??? # 1.send_data1= 3
??? # 2.receive_data2= 3
??? # 2.send_data2= 31
??? # 1.receive_data1= 31
??? # 1.send_data1= 4
??? # 2.receive_data2= 4
??? # 2.send_data2= 41
??? # 1.receive_data1= 41
??? # 1.send_data1= 5
??? # 2.receive_data2= 5
??? # 2.send_data2= 51
??? # 1.receive_data1= 51
??????
? ?----------------------------------------------------------------------------------------------------------------------------------------------------------------------

3.協程介紹 2018/8/15----------------------------------------------------------------- ''' 協程：是單線程下的并發，又稱微線程，纖程。英文名Coroutine。 缺點：#1. 無法利用多核，可開啟多進程，進程內開啟多線程，線程內開啟協程#2. 協程是單線程，一旦協程出現阻塞會阻塞整個線程 總結：必須在只有一個單線程里實現并發修改共享數據不需加鎖用戶程序里自己保存多個控制流的上下文棧 附加：一個協程遇到IO操作自動切換到其它協程（如檢測IO，yield、greenlet都無法實現，就用gevent模塊（select機制）說明：發生器也成為協同程序，這是一種更普遍的子程序形式。子程序在一點輸入并在另一點（函數頂部和一個 return語句）退出，可以在許多不同的點（yield語句）輸入，退出和恢復協程。使用yield實現協程： --------------------------------------------------------------------------- #************************************************************************** ''' import timedef people(name):print("Ready buy product ....")while True:receive_data2= yield # 程序暫停等待nextprint("{} is eating {}...".format(name,receive_data2))def factory():boy.__next__() # 實例boy啟動yieldgirl.__next__() # 實例girl啟動yieldi = 0while i<5:i += 1print("productNO: {}".format(i))boy.send(i) # 向yield發送數據，yield恢復，并自動執行nextgirl.send(i) # 向yield發送數據，yield恢復，并自動執行nexttime.sleep(1) #************************************************************************** boy = people("Tom") # 創建實例boy girl = people("Alice") # 創建實例girl product = factory() # 啟動函數p #************************************************************************** #>>> #Ready buy product .... #Ready buy product .... #productNO: 1 #Tom is eating 1... #Alice is eating 1... #productNO: 2 #Tom is eating 2... #Alice is eating 2... #productNO: 3 #Tom is eating 3... #Alice is eating 3... #productNO: 4 #Tom is eating 4... #Alice is eating 4... #productNO: 5 #Tom is eating 5... #Alice is eating 5... #>>> ------------------------------------------------------------------------------

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