Cilk Plus

Cilk, Cilk++ and Cilk Plus are general-purpose programming languages designed for multithreaded parallel computing. They are based on the C and C++ programming languages, which they extend with constructs to express parallel loops and the fork–join idiom.

Originally developed in the 1990s at the Massachusetts Institute of Technology (MIT) in the group of Charles E. Leiserson, Cilk was later commercialized as Cilk++ by a spinoff company, Cilk Arts. That company was subsequently acquired by Intel, which increased compatibility with existing C and C++ code, calling the result Cilk Plus.

The Cilk programming language grew out of three separate projects at the MIT Laboratory for Computer Science:

In April 1994 the three projects were combined and christened "Cilk". The name Cilk is not an acronym, but an allusion to "nice threads" (silk) and the C programming language. The Cilk-1 compiler was released in September 1994.

The original Cilk language was based on ANSI C, with the addition of Cilk-specific keywords to signal parallelism. When the Cilk keywords are removed from Cilk source code, the result should always be a valid C program, called the serial elision (or C elision) of the full Cilk program, with the same semantics as the Cilk program running on a single processor. Despite several similarities, Cilk is not directly related to AT&T Bell Labs' Concurrent C.

Cilk was implemented as a translator to C, targeting the GNU C Compiler (GCC). The last version, Cilk 5.4.6, is available from the MIT Computer Science and Artificial Intelligence Laboratory (CSAIL), but is no longer supported.

A showcase for Cilk's capabilities was the Cilkchess parallel chess-playing program, which won several computer chess prizes in the 1990s, including the 1996 Open Dutch Computer Chess Championship.