eventlet如何绿化pyserial最好

妙音 posted @ 2021年3月24日 19:19 in python with tags eventlet pyserial , 1118 阅读

问题

pyserial访问windows中的串口，如何绿化?不阻塞协程? 效率最高? 绿化毫无疑问要借用tpool.execute.

代码该如何实现才最佳呢？

方法一: 直接recv

直接recv，会阻塞协程

缺点: 协程被阻塞，程序不可用

方法二: tpool+in_waiting判断

import serial
from eventlet import tpool
class SerialSocket(serial.Serial):
    def recv(self):
        # 读完
        if self.in_waiting:
            return tpool.execute(self.read, self.in_waiting)
        return data

def listen_message():
    ss = SerialSocket("com10")
    buffer = b''
    while True:
        data = ss.recv()
        if data is not None:
            buffer +=data

缺点: cpu利用率较高

方法三: tpool+in_waiting判断+sleep

import serial
from eventlet import tpool, sleep
class SerialSocket(serial.Serial):
    def recv(self):
        # 读完
        if self.in_waiting:
            return tpool.execute(self.read, self.in_waiting)
        return data

def listen_message():
    ss = SerialSocket("com10")
    buffer = b''
    while True:
        data = ss.recv()
        if data is not None:
            buffer +=data
        else:
            sleep(0.01)

缺点: 满足大部分需求, 对时间要求比较敏感的程序，还是不行，多了0.01秒

方法四(完美)：tpool+in_waiting判断+read(1)阻塞

利用serial的read()阻塞特性，加上tpool线程，最终线程阻塞转换成协程阻塞

import serial
from eventlet import tpool

class SerialSocket(serial.Serial):
    def recv(self):
        # 等待
        data = tpool.execute(self.read, 1)
        # 读完
        while self.in_waiting:
            data += tpool.execute(self.read, self.in_waiting)
        return data

def listen_message():
    ss = SerialSocket("com10")
    buffer = b''
    while True:
        g = evenlet.spawn(ss.recv)
        data = g.wait()
        buffer +=data