Re:Friendship ended with the garbage collector
by throwaway81523 on Friday August 27, 2021 @05:39AM
(#28325851)
You might be right about that, i.e. I probably derped up. It's been a long while since I looked at it, and the issue might only be with shared_ptr. I'm starting to remember finding out that shared_ptr was surprisingly expensive even in single threaded programs. It looks like some finer grained versions of shared_ptr (like atomic_shared_ptr) arrived recently. I haven't checked into them yet.
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Re:Friendship ended with the garbage collector
by BenFrantzDale on Friday August 27, 2021 @08:34AM
(#28326993)
Typically unique_ptr is represented as a pointer (check sizeof). For shared_ptr, there’s an atomic refcount but no locks. Operations on the shared_ptr object itself aren’t threadsafe (you can’t have the same shared_ptr assigned by two threads at the same time without locking), just like int, but the reference count is atomic, so copies of shared_ptr can safely be shared among threads. Atomic_shared_ptr adds atomicity to the pointer itself. I believe that usually uses locks.