Native POSIX Thread Library: Difference between revisions

Revision as of 10:45, 14 August 2008

Revision as of 13:30, 12 November 2008

Line 7:

Before the 2.6 version of the [[Linux kernel]], processes were the schedulable entities, and there was no real support for [[Thread (computer science)|threads]]. However, it did support a [[system call]] - [[clone (Linux system call)|clone()]] - 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 thread support (most of the previous pthread implementations in Linux worked entirely in [[Userland (computing)|userland]]). Unfortunately, it had a number of issues with true POSIX compliance, 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 re-written threads 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]], and NPTL by developers at [[Red Hat]]. NGPT was abandoned in mid-[[2003]], at about the same time when NPTL was released.

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 (programming language)|Java]] website about Java on Red Hat Linux 9.<ref>[http://java.sun.com/developer/technicalArticles/JavaTechandLinux/RedHat/ Red Hat Linux 9 and Java 2 Platform, Standard Edition 1.4.2: A Winning Combination]</ref>