Synchronous vs Asynchronous Synchronous execution usually refers to code executing in sequence. Asynchronous execution refers to execution that doesn’t run in the sequence it appears in the code. In the following example, the synchronous operation causes the alerts to fire in sequence. In the async operation, while alert(2) appears to execute second, it doesn’t. Synchronous: … Read more
You probably want something like select.select() (see documentation). You supply select() with three lists of sockets: sockets you want to monitor for readability, writability, and error states. The server socket will be readable when a new client is waiting. The select() function will block until one of the socket states has changed. You can specify … Read more
The biggest advantage of nonblocking or asynchronous I/O is that your thread can continue its work in parallel. Of course you can achieve this also using an additional thread. As you stated for best overall (system) performance I guess it would be better to use asynchronous I/O and not multiple threads (so reducing thread switching). … Read more
It’s not possible for any library to do this without using some kind of asynchronous timer through threads or otherwise. The reason is that the timeout parameter used in httplib, urllib2 and other libraries sets the timeout on the underlying socket. And what this actually does is explained in the documentation. SO_RCVTIMEO Sets the timeout … Read more
I don’t understand how any of the proposed approaches that wrap JDBC calls in Actors, executors or anything else can help here – can someone clarify. Surely the basic problem is that the JDBC operations block on socket IO. When it does this it blocks the Thread its running on – end of story. Whatever … Read more
Using a separate thread is totally unnecessary. Just do this for your infinite while loop instead (Tested in Python 3.2.3). I use this technique in my eRCaGuy_PyTerm serial terminal program here (search the code for inWaiting() or in_waiting). import serial import time # Optional (required if using time.sleep() below) ser = serial.Serial(port=”COM4″, baudrate=9600) while (True): … Read more
In the case of a non blocking socket that has no data available, recv will throw the socket.error exception and the value of the exception will have the errno of either EAGAIN or EWOULDBLOCK. Example: import sys import socket import fcntl, os import errno from time import sleep s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((‘127.0.0.1’,9999)) fcntl.fcntl(s, fcntl.F_SETFL, … Read more
Example using C++11: #include <iostream> #include <future> #include <thread> #include <chrono> static std::string getAnswer() { std::string answer; std::cin >> answer; return answer; } int main() { std::chrono::seconds timeout(5); std::cout << “Do you even lift?” << std::endl << std::flush; std::string answer = “maybe”; //default to maybe std::future<std::string> future = std::async(getAnswer); if (future.wait_for(timeout) == std::future_status::ready) answer = … Read more
I want to add an example: #include <unistd.h> #include <fcntl.h> #include <stdio.h> int main(int argc, char const *argv[]) { char buf[20]; fcntl(0, F_SETFL, fcntl(0, F_GETFL) | O_NONBLOCK); sleep(4); int numRead = read(0, buf, 4); if (numRead > 0) { printf(“You said: %s”, buf); } } When you run this program you have 4 seconds to … Read more
ThreadPool.QueueUserWorkItem(o => FireAway()); (five years later…) Task.Run(() => FireAway()); as pointed out by luisperezphd.