Synchronization services

QNX Neutrino provides the POSIX-standard thread-level synchronization primitives, some of which are useful even between threads in different processes.

The synchronization services include at least the following:

Synchronization service	Supported between processes	Supported across a QNX LAN
Mutexes	Yes	No
Condvars	Yes	No
Barriers	No	No
Sleepon locks	No	No
Reader/writer locks	Yes	No
Semaphores	Yes	Yes (named only)
FIFO scheduling	Yes	No
Send/Receive/Reply	Yes	Yes
Atomic operations	Yes	No

The above synchronization primitives are implemented directly by the kernel, except for:

barriers, sleepon locks, and reader/writer locks (which are built from mutexes and condvars)
atomic operations (which are either implemented directly by the processor or emulated in the kernel)

Note: You should allocate mutexes, condvars, barriers, reader/writer locks, and semaphores, as well as objects you plan to use atomic operations on, only in normal memory mappings. On certain processors (e.g., some PPC ones), atomic operations and calls such as pthread_mutex_lock() will cause a fault if the object is allocated in uncached memory.