why concurrentQueue.sync DON'T cause deadlock
This code will deadlock because:
- they are in same thread
- print(2) has to wait print(3)
- print(3) has to wait print(2)
For example:
DispatchQueue.main.async {
print(Thread.current)
DispatchQueue.main.sync {
print(Thread.current)
print(2)
}
print(3)
}
Why in the concurrentQueue won't cause deadlock? They are also in same thread.
DispatchQueue.global().async {
print(Thread.current)
DispatchQueue.global().sync {
print(Thread.current)
print(2)
}
print(3)
}
ios concurrency grand-central-dispatch deadlock
edited Dec 22 '18 at 2:15
Rob
298k49556726
asked Nov 14 '18 at 5:56
pangyuleipangyulei
66
add a comment |
This code will deadlock because:
- they are in same thread
- print(2) has to wait print(3)
- print(3) has to wait print(2)
For example:
DispatchQueue.main.async {
print(Thread.current)
DispatchQueue.main.sync {
print(Thread.current)
print(2)
}
print(3)
}
Why in the concurrentQueue won't cause deadlock? They are also in same thread.
DispatchQueue.global().async {
print(Thread.current)
DispatchQueue.global().sync {
print(Thread.current)
print(2)
}
print(3)
}
ios concurrency grand-central-dispatch deadlock
edited Dec 22 '18 at 2:15
Rob
298k49556726
asked Nov 14 '18 at 5:56
pangyuleipangyulei
66
add a comment |
This code will deadlock because:
- they are in same thread
- print(2) has to wait print(3)
- print(3) has to wait print(2)
For example:
DispatchQueue.main.async {
print(Thread.current)
DispatchQueue.main.sync {
print(Thread.current)
print(2)
}
print(3)
}
Why in the concurrentQueue won't cause deadlock? They are also in same thread.
DispatchQueue.global().async {
print(Thread.current)
DispatchQueue.global().sync {
print(Thread.current)
print(2)
}
print(3)
}
ios concurrency grand-central-dispatch deadlock
edited Dec 22 '18 at 2:15
Rob
298k49556726
asked Nov 14 '18 at 5:56
pangyuleipangyulei
66
This code will deadlock because:
- they are in same thread
- print(2) has to wait print(3)
- print(3) has to wait print(2)
For example:
DispatchQueue.main.async {
print(Thread.current)
DispatchQueue.main.sync {
print(Thread.current)
print(2)
}
print(3)
}
Why in the concurrentQueue won't cause deadlock? They are also in same thread.
DispatchQueue.global().async {
print(Thread.current)
DispatchQueue.global().sync {
print(Thread.current)
print(2)
}
print(3)
}
ios concurrency grand-central-dispatch deadlock
ios concurrency grand-central-dispatch deadlock
edited Dec 22 '18 at 2:15
Rob
298k49556726
asked Nov 14 '18 at 5:56
pangyuleipangyulei
66
edited Dec 22 '18 at 2:15
Rob
298k49556726
asked Nov 14 '18 at 5:56
pangyuleipangyulei
66
edited Dec 22 '18 at 2:15
Rob
298k49556726
edited Dec 22 '18 at 2:15
Rob
298k49556726
edited Dec 22 '18 at 2:15
Rob
298k49556726
298k49556726
asked Nov 14 '18 at 5:56
pangyuleipangyulei
66
asked Nov 14 '18 at 5:56
pangyuleipangyulei
66
asked Nov 14 '18 at 5:56
pangyuleipangyulei
66
66
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
You ask:
Why in the
concurrentQueuewon't cause deadlock? They are also in same thread.
No, they're not in the same thread. They're in the same queue, but not the same thread.
This is the whole idea behind "concurrent queues" is that they can run individual dispatched tasks on different threads. That's how they permit concurrent operation. One dispatched task on concurrent queue can run on one thread while another dispatched task on that same queue can run on a separate thread.
As the old Concurrency Programming Guide says in its definition of a "concurrent queue":
The currently executing tasks run on distinct threads that are managed by the dispatch queue.
Or, as the DispatchQueue documentation says:
DispatchQueuemanages the execution of work items. Each work item submitted to a queue is processed on a pool of threads managed by the system. [emphasis added]
answered Dec 22 '18 at 2:13
RobRob
298k49556726
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
You ask:
Why in the
concurrentQueuewon't cause deadlock? They are also in same thread.
No, they're not in the same thread. They're in the same queue, but not the same thread.
This is the whole idea behind "concurrent queues" is that they can run individual dispatched tasks on different threads. That's how they permit concurrent operation. One dispatched task on concurrent queue can run on one thread while another dispatched task on that same queue can run on a separate thread.
As the old Concurrency Programming Guide says in its definition of a "concurrent queue":
The currently executing tasks run on distinct threads that are managed by the dispatch queue.
Or, as the DispatchQueue documentation says:
DispatchQueuemanages the execution of work items. Each work item submitted to a queue is processed on a pool of threads managed by the system. [emphasis added]
answered Dec 22 '18 at 2:13
RobRob
298k49556726
add a comment |
You ask:
Why in the
concurrentQueuewon't cause deadlock? They are also in same thread.
No, they're not in the same thread. They're in the same queue, but not the same thread.
This is the whole idea behind "concurrent queues" is that they can run individual dispatched tasks on different threads. That's how they permit concurrent operation. One dispatched task on concurrent queue can run on one thread while another dispatched task on that same queue can run on a separate thread.
As the old Concurrency Programming Guide says in its definition of a "concurrent queue":
The currently executing tasks run on distinct threads that are managed by the dispatch queue.
Or, as the DispatchQueue documentation says:
DispatchQueuemanages the execution of work items. Each work item submitted to a queue is processed on a pool of threads managed by the system. [emphasis added]
answered Dec 22 '18 at 2:13
RobRob
298k49556726
add a comment |
You ask:
Why in the
concurrentQueuewon't cause deadlock? They are also in same thread.
No, they're not in the same thread. They're in the same queue, but not the same thread.
This is the whole idea behind "concurrent queues" is that they can run individual dispatched tasks on different threads. That's how they permit concurrent operation. One dispatched task on concurrent queue can run on one thread while another dispatched task on that same queue can run on a separate thread.
As the old Concurrency Programming Guide says in its definition of a "concurrent queue":
The currently executing tasks run on distinct threads that are managed by the dispatch queue.
Or, as the DispatchQueue documentation says:
DispatchQueuemanages the execution of work items. Each work item submitted to a queue is processed on a pool of threads managed by the system. [emphasis added]
answered Dec 22 '18 at 2:13
RobRob
298k49556726
You ask:
Why in the
concurrentQueuewon't cause deadlock? They are also in same thread.
No, they're not in the same thread. They're in the same queue, but not the same thread.
This is the whole idea behind "concurrent queues" is that they can run individual dispatched tasks on different threads. That's how they permit concurrent operation. One dispatched task on concurrent queue can run on one thread while another dispatched task on that same queue can run on a separate thread.
As the old Concurrency Programming Guide says in its definition of a "concurrent queue":
The currently executing tasks run on distinct threads that are managed by the dispatch queue.
Or, as the DispatchQueue documentation says:
DispatchQueuemanages the execution of work items. Each work item submitted to a queue is processed on a pool of threads managed by the system. [emphasis added]
answered Dec 22 '18 at 2:13
RobRob
298k49556726
edited Dec 22 '18 at 18:16
answered Dec 22 '18 at 2:13
RobRob
298k49556726
answered Dec 22 '18 at 2:13
RobRob
298k49556726
answered Dec 22 '18 at 2:13
RobRob
298k49556726
298k49556726
add a comment |
add a comment |
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