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CONCURRENCY
VS
PARALLELISM
Narendran
@DudeWhoCode
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$ WHO AM I
Naren
Senior Software Consultant
Tarka Labs
Cycling | Travelling | Blogging
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@DudeWhoCode
blog.dudewho.codes
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SYNC VS ASYNC
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CONCURRENT VS PARALLEL
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CONCURRENT VS PARALLEL
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RECAP
• Sync: Blocking operations.
• Async: Non blocking operations.
• Concurrency: Making progress together.
• Parallelism: Making progress in parallel.
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CONCURRENCY IS NOT PARALLELISM
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CONCURRENCY IS NOT PARALLELISM
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CONCURRENCY IN PYTHON
3
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ASYNCIO
• Python 3 standard library to write single-threaded
concurrent code
• Introduced in python 3.4
• Inspired from “twisted” library
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ASYNCIO
• Event Loops
• Coroutines
• Futures
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EVENT LOOP
• Manages and distributes the execution of different
tasks.
•Responsible for registering the tasks and distributing
flow of control between them
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COROUTINES
•Special functions capable of releasing the flow of
control back to the event loop.
•Similar to python generators
•A coroutine is scheduled using an event loop
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FUTURES
•Objects that represent the result of a task.
•Task can be completed or pending.
•Object may be exceptions too.
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FLOW OF EXECUTION
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DIVING DEEP INTO CONCURRENCY…
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CONTEXT SWITCH
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BLOCKING TASKS
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ORDER OF EXECUTION
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SYNC VS ASYNC HTTP CALLS
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RETURN WHEN
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CANCEL FUTURE
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WAIT TIMEOUT
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CONCURRENCY VS PARALLELISM
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PARALLEL HTTP CALL
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CONCURRENT HTTP CALL
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CONCURRENCY VS PARALLELISM
BENCHMARK VIDEO
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HOW CONCURRENCY IS DIFFERENT FROM
MULTI-THREADING?
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THREADING VS ASYNC
• Async : Mostly single threaded, You decide when
a piece of code can take back control using await
• Threading : Python scheduler takes care of
context switch and it may lose control anytime.
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SUMMARY
• Sync: Blocking operations.
• Async: Non blocking operations.
• Concurrency: Creating subtasks, scheduling subtasks,
switching between them, making progress together.
• Parallelism: Creating subtasks, utilize CPU core,
making progress in parallel.
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SUMMARY
• Python 3, asyncio, aiohttp, aiofiles
• Eventloops, co-routines, futures
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SUMMARY
• context switching
• sync vs async http calls
• no order of execution
• return_when
• cancel pending future
• wait timeout
• parallel vs concurrent http calls
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REFERENCES
• AsyncIO for the Working Python Developer (Hackernoon)
- Yeray Diaz
• A guide to asynchronous programming in Python with asyncio
(FreeCodeCamp)
- Roman Gaponov
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THANK YOU,
NAREN
@DudeWhoCode
Slides:
www.dudewho.codes/talks
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