C++ using this pointer in constructors

c++ constructor multithreading this
gilbertc picture gilbertc · Mar 25, 2010 · Viewed 21.3k times · Source

In C++, during a class constructor, I started a new thread with this pointer as a parameter which will be used in the thread extensively (say, calling member functions). Is that a bad thing to do? Why and what are the consequences?

My thread start process is at the end of the constructor.

Answer

David Rodríguez - dribeas picture David Rodríguez - dribeas · Mar 25, 2010

The consequence is that the thread can start and code will start executing a not yet fully initialized object. Which is bad enough in itself.

If you are considering that 'well, it will be the last sentence in the constructor, it will be just about as constructed as it gets...' think again: you might derive from that class, and the derived object will not be constructed.

The compiler may want to play with your code around and decide that it will reorder instructions and it might actually pass the this pointer before executing any other part of the code... multithreading is tricky

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