The Native POSIX Thread Library (NPTL) is an implementation of the POSIX Threads specification for the

Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...

operating system.

History

Before the 2.6 version of the

Linux kernel The Linux kernel is a Free and open-source software, free and open source Unix-like kernel (operating system), kernel that is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the k ...

, processes were the schedulable entities, and there were no special facilities for threads. However, it did have a

system call In computing, a system call (syscall) is the programmatic way in which a computer program requests a service from the operating system on which it is executed. This may include hardware-related services (for example, accessing a hard disk drive ...

— — which creates a copy of the calling process where the copy shares the address space of the caller. The LinuxThreads project used this system call to provide kernel-level threads (most of the previous thread implementations in Linux worked entirely in userland). Unfortunately, it only partially complied with POSIX, particularly in the areas of signal handling, scheduling, and inter-process synchronization primitives. To improve upon LinuxThreads, it was clear that some kernel support and a new threading library would be required. Two competing projects were started to address the requirement: NGPT (Next Generation POSIX Threads) worked on by a team which included developers from

IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...

, and NPTL by developers at

Red Hat Red Hat, Inc. (formerly Red Hat Software, Inc.) is an American software company that provides open source software products to enterprises and is a subsidiary of IBM. Founded in 1993, Red Hat has its corporate headquarters in Raleigh, North ...

. The NGPT team collaborated closely with the NPTL team and combined the best features of both implementations into NPTL. The NGPT project was subsequently abandoned in mid-2003 after merging its best features into NPTL. NPTL was first released in Red Hat Linux 9. Old-style Linux POSIX threading is known for having trouble with threads that refuse to yield to the system occasionally, because it does not take the opportunity to preempt them when it arises, something that Windows was known to do better at the time. Red Hat claimed that NPTL fixed this problem in an article on the

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

website about Java on Red Hat Linux 9. NPTL has been part of

Red Hat Enterprise Linux Red Hat Enterprise Linux (RHEL) is a commercial Linux distribution developed by Red Hat. Red Hat Enterprise Linux is released in server versions for x86-64, Power ISA, ARM64, and IBM Z and a desktop version for x86-64. Fedora Linux and ...

since version 3, and in the Linux kernel since version 2.6. It is now a fully integrated part of the

GNU C Library The GNU C Library, commonly known as glibc, is the GNU Project implementation of the C standard library. It provides a wrapper around the system calls of the Linux kernel and other kernels for application use. Despite its name, it now also dir ...

.GNU C Library version 2.3.3 release
/ref> There exists a tracing tool for NPTL, calle
POSIX Thread Trace ToolPTT
. And a
Open POSIX Test SuiteOPTS
was written for testing the NPTL library against the POSIX standard.

Design

Like LinuxThreads, NPTL is a 1:1 threads library. Threads created by the library (via ''pthread_create'') correspond one-to-one with schedulable entities in the kernel (''processes'', in the Linux case). This is the simplest of the three threading models (1:1, N:1, and M:N). New threads are created with the clone()

called through the NPTL library. NPTL relies on kernel support for futexes to more efficiently implement user-space locks.

References

External links

NPTL Trace Tool
OpenSource tool to trace and debug multithreaded applications using the NPTL. {{DEFAULTSORT:Native Posix Thread Library Linux kernel C POSIX library Threads (computing)

History

Design

See also

References

External links