1. GCD
(Grand Central Dispatch)
iOS & OS X 멀티스레딩 기법
2013. 11.
아프리카TV 기술연구소 모바일개발팀
전임연구원 정창욱

2. Concurrent, Multi threading and processing
● OpenMP
● OpenCL
● GCD

9. GCD의 특징
● Multi Thread and Processing 코드를 간결하
고 쉽게 구현 가능
● C 언어로 되어 있는 Thread 관리 기술
● C 언어의 Block 기반으로 실행
● OS가 지능적으로 Task(Thread) 스케쥴링

10. GCD - Dispatch Queue Type
OS kernal
Dispatch Queue
4
3
2
1
run
worker thread

11. GCD - Dispatch Queue Type
Serial Dispatch Queue
3
2
1
run
worker thread
Concurrent Dispatch Queue
run
worker thread
3
2
1
run
worker thread
run
worker thread

12. GCD - Dispatch Queue Type
Serial - Main Dispatch Queue
Concurrent - Global Dispatch Queue

13. GCD - 생성 및 얻기
● dispatch_queue_t dispatch_queue_create(
const char *label,
dispatch_queue_attr_t attr);
● dispatch_queue_t dispatch_get_main_queue(void);
● dispatch_queue_t dispatch_get_global_queue(
long priority,
unsigned long flags);

14. GCD - 실행 및 제어
●
●
●
void dispatch_async(
dispatch_queue_t queue,
dispatch_block_t block);
void dispatch_barrier_async(
dispatch_queue_t queue,
dispatch_block_t block);
void dispatch_sync(
dispatch_queue_t queue,
dispatch_block_t block);
Concurrent dispatch queue
dispatch_async
dispatch_async
task
task
task
task
task
task
task
dispatch_barrier_async
시간

15. GCD - 실행 및 제어
●
void dispatch_apply(
size_t iterations,
dispatch_queue_t queue,
void (^block)(size_t));

16. GCD - 실행 및 제어
● void dispatch_set_target_queue(
dispatch_object_t object,
dispatch_queue_t queue);
● void dispatch_after(
dispatch_time_t when,
dispatch_queue_t queue,
dispatch_block_t block);

17. GCD - 실행 및 제어
● void dispatch_group_async(
dispatch_group_t group,
dispatch_queue_t queue,
dispatch_block_t block);
● void dispatch_group_notify(
dispatch_group_t group,
dispatch_queue_t queue,
dispatch_block_t block);

18. GCD - 실행 및 제어
● void dispatch_suspend(dispatch_object_t object);
● void dispatch_resume(dispatch_object_t object);
● void dispatch_once(
dispatch_once_t *predicate,
dispatch_block_t block);