Efficient C++ Performance Programming Techniques

Share Nothing

Reduction in sharing is good, but nothing beats eliminating contention altogether. Instead of sharing a resource, you can sometimes eliminate sharing completely by giving each thread its own private resource. Recall from the previous section that each Web server worker thread (in our implementation) maintained a pointer to its private data object of type ThreadSpecificData:

class ThreadSpecificData {
    HTRequest *reqPtr;   // Attributes of current HTTP request
    ...
};

The reqPtr member was a pointer to an HTRequest object containing information about the current HTTP request. At the beginning of each request, the worker thread created a brand new object of type HTRequest:

 ThreadSpecificData *HTInitRequest(StreamSocket sock) { ... ...