In the example given in this chapter, we saw how to share information between threads in addition to synchronizing threads--this in the form of the requests we passed from the main thread into the dispatcher from which each request gets passed on to a different thread.
The essential idea behind the sharing of data between threads is that the data to be shared exists somewhere in a way which is accessible to two threads or more. After this, we have to ensure that only one thread can modify the data, and that the data does not get modified while it's being read. Generally, we would use mutexes or similar to ensure this.
Read-write locks are a possible optimization here, because they allow multiple threads to read simultaneously from a single data source. If one has an application in which multiple worker threads read the same information repeatedly, it would be more efficient to use read-write locks than basic mutexes, because the attempts to read the data will not...