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Use Shared Objects on LinuxBy Sachin O. Agrawal2005-05-27 
Making shared memory work
You should consider two major issues when instantiating C++ objects within shared memory. First, the Vee-Table pointer is used to access virtual functions, and data members are accessed directly using compile time offsets. Hence, for all such shared objects, Vee-Table and virtual functions should have the same virtual addresses in all processes. There is no hard-and-fast rule for doing this, but adopting a proper link sequence for dependent shared libraries should work most of the time. In addition, keep in mind that virtually inherited objects have base pointers to address base objects. Base pointers refer to data sections of the process, and are always process specific. It is difficult to ensure the same numerical values for these across all client processes. Hence, construction of virtually inherited objects in shared memory should be avoided for the assumed C++ object model. But keep in mind, too, that different compilers adopt different models. For instance, Microsoft Compiler uses process-neutral offsets to address base objects for virtually inherited classes: thus, this issue does not arise. The important thing is to ensure the same addresses for shared libraries in all client-processes. Tutorial Pages: » Make shared memory work for you, not against you » Environmental assumptions » Sample program » Making shared memory work » Resources First published by IBM DeveloperWorks
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