The threads are making cooperative shared use of a single entity. Any time you are using multiple threads in Frontier, you should consider whether you need a semaphore to keep them from trying to access the same entity simultaneously. Here, our example was a database entry. Another might be a file on disk. Another might be a line of communication to an application that isn't multithreaded.
Semaphores are purely a voluntary, cooperative device.
Here is how semaphores really work. Then, it adds the name to the registry. The danger with semaphores is failure to unlock one, which will cause any other thread that tries to lock the same semaphore to be unable to proceed. In case of trouble, the semaphores table can also be cleaned out manually, by quitting and restarting Frontier, or by choosing Unlock Semaphores from the Web menu. One final note about the names of the verbs.