Multicore Application Programming: For Windows, Linux, and Oracle® Solaris

4. Synchronization and Data Sharing

For a multithreaded application to do useful work, it is usually necessary for some kind of common state to be shared between the threads. The degree of sharing that is necessary depends on the task. At one extreme, the only sharing necessary may be a single number that indicates the task to be performed. For example, a thread in a web server might be told only the port number to respond to. At the other extreme, a pool of threads might be passing information constantly among themselves to indicate what tasks are complete and what work is still to be completed. Beyond sharing to coordinate work, there is sharing common data. For example, all threads might be updating a database, or all threads might be responsible ...