Concurrency From the Ground Up

What are the fundamental building blocks of concurrency underneath the APIs we use every day?

Presented at 360iDev 2018.

Transcript

1. Concurrency
 From the
 Ground Up @gregheo 360iDev 2018 {
2. @gregheo 360iDev 2018 Concurrency
3. @gregheo 360iDev 2018 1. Programs that seem faster to the user 2. Programs that are easy to understand for the programmer WHY? WHY?
4. @gregheo 360iDev 2018 1. Structuring our programs better 2. Thinking in terms of Tasks 3. Protecting Resources
5. @gregheo 360iDev 2018 mainQueue.async { } troublesomeCode()
6. @gregheo 360iDev 2018 mainQueue.asyncAfter(.now + 0.1) { } troublesomeCode()
7. @gregheo 360iDev 2018 Concurrency
 &
 Structure
8. @gregheo 360iDev 2018 Concurrency
 Parallelism
9. @gregheo 360iDev 2018 “concurrency is the composition of independently executing processes”
10. @gregheo 360iDev 2018 “parallelism is the simultaneous execution of (possibly related) computations”
11. @gregheo 360iDev 2018 “parallelism is the simultaneous execution of computations”
12. @gregheo 360iDev 2018 “
 
 Parallelism is about doing lots of things at once.” Concurrency is about dealing with lots of things at once.
13. @gregheo 360iDev 2018
14. @gregheo 360iDev 2018
15. @gregheo 360iDev 2018
16. @gregheo 360iDev 2018 C B A A()
 B()
 C()
17. @gregheo 360iDev 2018 A B C
18. @gregheo 360iDev 2018 A B C
19. @gregheo 360iDev 2018 A B C data
20. @gregheo 360iDev 2018 Order? Shared state? Mutable state?
21. @gregheo 360iDev 2018 Tasks
 &
 Threads
22. @gregheo 360iDev 2018 thread function thread thread
23. @gregheo 360iDev 2018 pthread GCD queue NSOperation dispatch groups
24. @gregheo 360iDev 2018 Locks
 &
 Resources
25. @gregheo 360iDev 2018 Lock • Locks as signals • Locks as mutual exclusion
26. @gregheo 360iDev 2018 pthread mutex semaphore os_unfair_lock NSLock GCD
 semaphore dispatch
 groups
27. @gregheo 360iDev 2018 1. Structuring our programs better 2. Thinking in terms of Tasks 3. Protecting Resources
28. @gregheo 360iDev 2018 1. Programs that seem faster to the user 2. Programs that are easy to understand for the programmer
29. @gregheo 360iDev 2018 pthread GCD
 queue Groups pthread
 mutex unfair lock NSLock GCD
 semaphore pthread
 semaphore NSThread }