Facebook publishes internal C++ software library

Facebook has released a library of C++ software components used to help run its site, the social networking company announced yesterday..

By releasing this library, called Folly, Facebook will be able to release more of its internal programs as open source, because they rely on different components in this library.

"One clear bottleneck to releasing more work has been that any open sourced project needed to break dependencies on unreleased internal library code," wrote Facebook software engineer Jordan DeLong, who posted an entry on Facebook announcing the release.

Facebook engineers also announced the release at a C++ conference the company held on Saturday at its campus at Menlo Park, California.

Facebook has relied on open-source software, such as MySQL, PHP and memcached, to run its sites. And so the company has made a point of releasing its own internal programs as open-source software as well, such as the HipHop PHP compiler and the Thrift service sharing framework.

For many of its open source releases though, Facebook developers have had to rewrite some of the functionality that was borrowed from this library. By releasing the library itself, Facebook will be able to "continue open sourcing parts of [its] stack without resorting to reinventing ... internal wheels," DeLong wrote.

Even if developers don't plan on using Facebook developed applications, they should still take a look at this library, as it includes many utilities of possible to use in other environments, DeLong said. Many of the components available in Folly run more quickly than their equivalents available elsewhere, he boasted. "Our motivation was to build components that were faster and more efficient than what we previously used," he wrote. These utilities were designed to be used in heavy production environments, across thousands of servers.

The components cover a range of functionality. One component was designed to use memory more efficiently. Another reduces contention. The AtomicHashMap utility cuts the amount of time a piece of data in memory is locked by an operation, which can slow performance and cause bottlenecks in heavily used environments. A set of string manipulation components use fewer CPU cycles than formatters in other C++ libraries, DeLong boasted.

The Folly library is posted on GitHub, and Facebook will add new components as they are written, according to DeLong