Open Sourcing Cilk Plus

When did Intel Cilk Plus become an open source project?

Intel announced the creation of an open source project for Intel Cilk Plus on August 9, 2011. Intel emphasized its commitment to making Cilk Plus a viable and strong option for expressing concurrency in C and C++ by announcing at the same time that it was implementing Intel Cilk Plus in the C and C++ compilers of the GNU Compiler Collection (GCC).

Intel Cilk Plus is now available as an open source project under the GNU General Public License version three (GPLv3) with the Runtime Library Exception.

Why was it important to open source Intel Cilk Plus?

Multi-core processors are nearly ubiquitous now. Software developers can program for concurrency in their application to take full advantage of multi-core processors. The importance of doing this only increases over time. A program deployed today may be running on quad-core processors or even systems with multiple quad-core processors. That same program, if it is used for 3 years, may eventually run on systems with 8 or 16 core processors or more. Intel Cilk Plus helps ensure that applications can be written for the architectures of tomorrow while targeting the systems of today.

Why did you not open source originally?

We had certain objectives we wanted to meet before open sourcing. We wanted to be sure we had perfected Intel Cilk Plus as an easy and effective way to help real applications. Our focus is helping developers write scalable C and C++ code, or help developers move to parallel systems. Waiting to release under open source gave us some time and feedback on what we needed to do with Intel Cilk Plus.

Why open source now?

Customer feedback regarding Intel Cilk Plus, since Intel launched it in August 2011, has been hugely positive, with two exceptions. Customers told Intel they want to use Intel Cilk Plus – because it is wonderful – but they needed two things:

1. EVERYWHERE: make it available on more OSes and for more processors.

2. FOREVER: make it permanent. While exclusively a proprietary product from Intel – some feared depending on it for all parallel programming because it might cease to exist if Intel cancelled the project.

We concluded that adding staff to the project and open sourcing it (doing both, together) was the best solution to the problem. We also responded to customers who said was important to continue to offer a commercial version and support from Intel.

What will be Intel's role going forward?

Intel engineers will act as the maintainers of the project, and help maintain a vision and passion for parallelism. The project is dedicated to supporting all compilers, all OSes and all processors as a cornerstone for the project. Intel is very committed to the success of the project and has added more people to the project as well as committed ourselves to be responsive to inquiries and contributions.

How does the open source version of Intel Cilk Plus differ from the commercial version?

The open source version of Intel Cilk Plus should be functionally identical to the commercial version.  Currently there are no differences, and there are no plans to change that. We plan to maintain one source base and do builds for both from the same source base. Intel offers its standard commercial support for purchasers of the Intel® Parallel Studio XE suites, and for the open source version will refer people to the open source web site for FAQs, forums and the like for support.

At this time Windows* is only supported by the commercial version of Intel Cilk Plus.

Will Intel continue to offer support?

Yes. Intel continues to support the commercial version of Intel Cilk Plus which is shipped as part of the Intel® Parallel Studio XE suites.