Network Programming Basics-Multi-threaded---concurrent.futures module---event---semaphore semaphore---timer timer---deadlock phenomenon recursive lock----thread queues queue

1 concurrent.futures module:

#From ABC import Abstractmethod,abcmeta##class A (Metaclass=abcmeta):#def mai (self):#Pass#@classmethod#class B (A):#def mai (self):#Pass#Abstract class----defines some interface standards for subclasses @abstractmethod=================== process pool and thread pool ===================the concept of introducing pools is to control the number of Concurrent.futures =======>>> asynchronous calls # 1 ====== shutdown (wait=true) ====>> close () +joi N () shutdown (wait=false) =======>> Close () # 2 ====== submit ===>> Apply_async () # 3 ====== map=====# 4 = = ==add_done_callback (FN) fromConcurrent.futuresImportThreadpoolexecutor,processpoolexecutorImportTime,random,os=============================== Compute multiple process pools ==================================================#def work (n):#print ('%s is running '%os.getpid ())#Time.sleep (Random.randint (1,3))#return n*n## 1#if __name__ = = ' __main__ ':#Executor_p=processpoolexecutor (4)#futures=[]#For I in Range (Ten):#Future=executor_p.submit (work,i) # Gets the result of the asynchronous commit's future object#futures.append (future)#Executor_p.shutdown (wait=true) # executor_p = Shutdown#print (' main ')#For obj in futures:#print (Obj.result ()) # results### 2 ===== with AS#if __name__ = = ' __main__ ':#With Processpoolexecutor (4) as E:#futures=[]#For I in range (6):#future=e.submit (work,i)#futures.append (future)#print (' Main ')#For obj in futures:#print (Obj.result ())#================================ shorthand ===========================================# from Concurrent.futures import threadpoolexecutor# from threading import current_thread,enumerate,active_count## def work (n): # print ('%s is running '%current_thread ()) # return n**2## if __name__ = = ' __main__ ': # with THREADPO Olexecutor () as executor:# Futures=[executor.submit (work,i) for I in range (+)]## for I in futures:# P Rint (I.result ())=======================================  io multiple thread pool ===========================##def work (n):#print ('%s is running '%os.getpid ())#Time.sleep (Random.randint (1,3))#return n*n## 1#if __name__ = = ' __main__ ':#Executor_p=threadpoolexecutor (+)#futures=[]#For I in Range (Ten):#Future=executor_p.submit (work,i) # Gets the result of the asynchronous commit's future object#futures.append (future)#Executor_p.shutdown (wait=true) # executor_p = Shutdown#print (' main ')#For obj in futures:#print (Obj.result ()) # results### 2 ===== with AS#if __name__ = = ' __main__ ':#With Threadpoolexecutor (+) as E:#futures=[]#For I in range (6):#future=e.submit (work,i)#futures.append (future)#print (' Main ')#For obj in futures:#print (Obj.result ())===========================  map ======== Loop submits multiple results ================================= ===
#From concurrent.futures import threadpoolexecutor#From threading Import Current_thread,enumerate,active_count##def work (n):#print ('%s is running '%current_thread ())#return n**2##if __name__ = = ' __main__ ':#With Threadpoolexecutor () as executor:#Futures=[executor.map (Work,range (+))]#[1,2,3,4,5]#Executor.map (Work,range (6)) passes the back iteration object as a parameter to the work#===============================future.add_done_callback (FN)======== callback function ========================== ===================##From concurrent.futures import processpoolexecutor##def work (n):#return n**n##def WORK2 (m):#M=m.result ()#print (M/2)##if __name__ = = ' __main__ ':#With Processpoolexecutor () as E:#For I in range (6):#E.submit (work,i). Add_done_callback (WORK2)#======================future.exeption (4) ======== wait Time-wait Timeout exception =============================================  

2. Event:

collaborative work between two processes fromThreadingImportEvent,current_thread,threadImportTime 
e =Event () defcheck ():Print('%s is detecting'%Current_thread (). GetName ()) Time.sleep (3) e.set ()  #  confirm Settings defConn (): Count=1 while  notE.is_set ():ifCount >3:            RaiseTimeouterror ('Connection timed out')        Print('%s is waiting for connection'%Current_thread (). GetName ()) e.wait (Timeout =0.1) # time-out limit number of attempts Count+=1Print('%s is connecting'%Current_thread (). GetName ())if __name__=='__main__': T1=thread (target=check) T2=thread (target=conn) T3=thread (target=conn) T4=thread (target=conn) T1.start () T2.start () T3.start () T4.start ()

3. Signal Volume semaphore:

 from Import Semaphore  semaphore Semaphore---Essence is a lock ====== control the number of simultaneous processes (more processes can be opened in the background) process Pool  ----number of processes running concurrently () 

4.-Timers Timer:

# From threading Import Timer ## def hello (): #      print (' Hello ')##  t=timer (4,hello)  # timer--is a subclass of thread  4 seconds after start #  T.start ()

5. Deadlock Phenomenon Recursive Lock:

============================== deadlock Phenomenon ================================= recursive lock rlock---can be aquire multiple timesOne count per aquire plus one, as long as the count is not one can not be grabbed by other threads Mutex ----can only be aquire once fromThreadingImportThread,lock,current_threadImportTimemutexa=Lock () Mutexb=Lock ()classMythread (Thread):defRun (self): Self.f1 () self.f2 ( )defF1 (self): with Mutexa:Print('%s grabbed a.'%Current_thread (). GetName ()) with Mutexb:Print('got a B.'%Current_thread (). GetName ())defF2 (self): with Mutexb:Print('got a B.'%Current_thread (). GetName ()) Time.sleep (0.1) with Mutexa:Print('grab A.'%Current_thread (). GetName ())if __name__=='__main__':     forIinchRange (6): T=Mythread () T.start ( )

6. Thread Queuing queue:

ImportQueueq=queue. Queue (4) Q.put (2) Q.put (2) Q.put (2) Q.put (2)Print(Q.get ())Print(Q.get ())Print(Q.get ())Print(Q.get ()) #  1 priority queue Q=queue. Priorityqueue (3) Q.put (10,'TSD')) Q.put (4,'ard'))#The same precedence compares the subsequent dataQ.put (10,'ASD'))#The smaller the number, the higher the priority .Print(Q.get ())Print(Q.get ())Print(Q.get ()) #  2 advanced post-out---stack queue Q=queue. Lifoqueue (3)

Network Programming Basics-Multi-threaded---concurrent.futures module---event---semaphore semaphore---timer timer---deadlock phenomenon recursive lock----thread queues queue