Hands-On System Programming with Linux

The cancelability type

Assuming the target thread has the cancelability state enabled is the first step; the thread's cancelability type determines what happens next. There are two types: deferred (the default) and asynchronous. When a thread's cancelability type is asynchronous, it can be canceled at any point in time (in fact, it should happen immediately, but is not always guaranteed to); if the cancelability type is deferred (the default), it can only be canceled (terminated) when it hits the next cancelation point.

A cancelation point is a list of (usually blocking) functions (more on this shortly). When the target thread—that, remember, is of the enabled cancelability state and the deferred type—encounters the next cancelation point ...