Речь пойдет о двух языках: Python и Javascript. Максим расскажет об асинхронной работе Python и Javascript, что даст возможность слушателям приобщиться к особой касте разработчиков, работающих с Twisted.

1. Asynchronous
programming
JS and python inside
Maxim Schepelin

3. Contents
● Python.
● What is call stack?
● Where callbacks come from?
● How asynchronous code execution works?
● Summary

4. Code: Call stack:
def multiply(x, y):
return x * y
def square(x):
return multiply(x, x)
def print_result(n):
result = square(n)
sys.stdout.write(result)
if __name__ == '__main__':
print_result(4)
multiply
square
print_result
main

5. Code: Call stack:
def foo():
foo()
if __name__ == '__main__':
foo()
foo
foo
foo
foo
foo
foo
foo
main
RuntimeError: maximum recursion depth exceeded

6. Contents
● Python.
● What is call stack?
● Where callbacks come from?
● How asynchronous code execution works?
● Summary

7. Code: Call stack:
console.log(1);
console.log(2);
setTimeout(function ( ) {
console.log(4);
}, 500);
console.log(3);
csoentTsiomlee.olougt
anonymous main
func

8. Code: Call stack:
console.log(1);
console.log(2);
setTimeout(function ( ) {
console.log(4);
}, 500);
console.log(3);
csoentTsiomlee.olougt
anonymous main
func
Browser engine:
Timer(cb)
Callback queue: callback
1
2
3

9. Contents
● Python.
● What is call stack?
● Where callbacks come from?
● How asynchronous code execution works?
● Summary

11. Asynchronous workflow
Call stack
Event-loop Async call
External API
Callback
queue

12. Code: Call stack:
console.log(1);
console.log(2);
setTimeout(function ( ) {
console.log(4);
}, 0);
console.log(3);
csoentTsiomlee.olougt
anonymous main
func
Browser engine:
Timer(cb)
Callback queue: callback
1
2
3

13. Callbacks are invoked
only when call stack is
emtpy!

14. Contents
● Python.
● What is call stack?
● Where callbacks come from?
● How asynchronous code execution works?
● Summary

15. Summary
● Asynchromous != multithreading
● Heavy things blocks the event-loop
● It’s still single thread

16. Q&A
schepelin
Maxim Schepelin