C++ Blog

Shared Memory based C++ programming

Posted in boost by Umesh Sirsiwal on January 5, 2009

When it comes to shared memory based programming, we C++ users have traditionally found our selves at disadvantage. Most our beloved constructs like shared pointers, various containers, scoped locks, etc. don’t work very well when programming in C++. In addition, we cannot place objects which use inheritance in shared memory since the virtual pointers cannot work in shared memory. These limitation has implied that the shared memory is rarely used in C++ programming. Whenever it is used, the object placed in the shared memory are more like C constructs rather then C++ constructs. This is pity since using shared memory provides significant performance advantage in certain conditions.

Boost 1.35 includes Interproces which provides C++ based programming environment for shared memory. The facilities provided are:

  • Shared memory based pool of memory and capability to new C++ objects from this pool
  • Mutexes placed in the shared memory
  • Various smart pointers
  • Various STL-like containers which can be placed in shared memory. These containers include maps, deque, set, list, flat_map, flat_set, slist, and string

In addition various boost containers can be placed in shared memory. These containers include the multi-index container.

Hopefully these constructs make placing objects in shared memory a little easier for you all. Please note that placing data in shared memory has traditionally been dangerous due to complexity in debugging crashes, not easily understood deadlocks, etc. Please use shared memory based containers carefully.