python - How to detect multiprocessing.Pipe is full? -

problem description: doing multiprocessing in python , using multiprocessing.pipe() communicate between processes. have been searching lot still couldn't find way detect whether pipe full or not. example below, writepipe process keeps putting number 2 different pipes (odd & even) , readpipe process continuously read these 2 pipes. however, speed of read odd pipe faster pipe full. @ moment, writepipe process blocked while readpipe process still keep waiting read odd pipe causes deadlock.

my question: there way can detect pipe full can stop putting number full pipe while still running , put number pipe still has spaces?

from multiprocessing import process, pipe   def writepipe(sendnumberodd, sendnumbereven):     = 0     while true:         if % 2 == 0:             sendnumbereven.send(i)         else:             sendnumberodd.send(i)         += 1  def readpipe(recvnumberodd, recvnumbereven):     counteven = 0     while true:         counteven += 1         print(counteven, recvnumbereven.recv())          countodd = 0         while countodd < 50:             countodd += 1             print (countodd, recvnumberodd.recv())    if __name__ == '__main__':     recvnumberodd, sendnumberodd = pipe(duplex=false)     recvnumbereven, sendnumbereven = pipe(duplex=false)      write = process(target=writepipe, args=(sendnumberodd, sendnumbereven))     read = process(target=readpipe, args=(recvnumberodd, recvnumbereven))     write.start()     read.start()      sendnumberodd.close()     sendnumbereven.close() 

proposal untested

class connection(multiprocessing.connection):     def __init__(self, maxsize=0):         self.__maxsize = maxsize         self.size = 0         self.__lock = multiprocessing.lock      def send(self, obj):         self.__lock:             self.size += sizeof(obj)         super().send(obj)      def recv(self):         _recv = super().recv()         self.__lock:             self.size -= sizeof(_recv)         return _recv      def full(self):         if self.__maxsize > 0:             return self.size >= self.__maxsize         return none  def pipe(maxsize=0, duplex=true):     return connection(maxsize), connection(maxsize) 

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implement poll() check if data ready.

python » documentation: poll([timeout])

return whether there data available read.   

for example:

if recvnumbereven.poll():     counteven += 1     print(counteven, recvnumbereven.recv()) 

alternative use wait(...) both

multiprocessing.connection.wait(object_list, timeout=none)

wait till object in object_list ready.   returns list of objects in object_list ready.