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TABLE 1–1 Multithreading Terms (Continued)
Term Denition
Solaris threads A Sun Microsystems threads interface that is not POSIX threads
compliant. A predecessor of pthreads.
Single-threaded Restricts access to a single thread. Execution is through sequential
processing, limited to one thread of control.
Multithreading Allows access to two or more threads. Execution occurs in more than
one thread of control, using parallel or concurrent processing.
User-level or Application-level
threads
Threads managed by threads routines in user space, as opposed to kernel
space. The POSIX pthreads and Solaris threads APIs are used to create
and handle user threads. In this manual, and in general, a thread is a
user-level thread.
Note – Because this manual is for application programmers, kernel
thread programming is not discussed.
Lightweight processes Kernel threads, also called LWPs, that execute kernel code and system
calls. LWPs are managed by the system thread scheduler, and cannot be
directly controlled by the application programmer. Beginning with
Solaris 9, every user-level thread has a dedicated LWP. This is known as a
1:1 thread model.
Bound thread (obsolete term) Prior to Solaris 9, a user-level thread that is permanently bound to one
LWP. Beginning with Solaris 9, every thread has a dedicated LWP, so all
threads are bound threads. The concept of an unbound thread no longer
exists.
Unbound thread (obsolete term) Prior to Solaris 9, a user-level thread that is not necessarily bound to one
LWP. Beginning with Solaris 9, every thread has a dedicated LWP, so the
concept of unbound threads no longer exists.
Attribute object Contains opaque data types and related manipulation functions. These
data types and functions standardize some of the congurable aspects of
POSIX threads, mutual exclusion locks (mutexes), and condition
variables.
Mutual exclusion locks Objects used to lock and unlock access to shared data. Such objects are
also known as mutexes.
Condition variables Objects used to block threads until a change of state.
Read-write locks Objects used to allow multiple read-only access to shared data, but
exclusive access for modication of that data.
Counting semaphore A memory-based synchronization mechanism in which a non-negative
integer count is used to coordinate access by multiple threads to shared
resources.
MultithreadingTerms
Multithreaded Programming Guide • November 2010 (Beta)18