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QString and many data structure of Qt are implicit sharing
How could I make their memory leak?
Circular dependency would cause memory leak if it is shared_ptr
Would QString and other QString like data structure in Qt memory leak too?
I want to know how to make the memory of QString leak, so I would not fall
into the trap of it.
After some study, looks like I don’t have to worry about circular dependency when
it is QString? Thanks to your reply, now I don’t have to worry about it.
In versions of Qt prior to 4 concurrent access to two copies of a QString which shared the same data could cause problems because QString is COW but did not lock the ref count. This was a gotcha. As of version 4 the ref count is handled using atomics which solves the problem.
You can mangle some Qt containers by putting things in them that can throw in odd places but I can’t think of a way that could affect QString. Be warry of exception handling in Qt, the doc’s are quite vague which usually means beware 😉
http://doc-snapshot.qt-project.org/4.8/exceptionsafety.html
If you run out of memory when running Qt expect the world to end, in that case it’s probably doesn’t matter if the QString leaked or not.