Mercurial Online Tutorials

Mackall first announced Mercurial on 19 April 2005. The impetus for this was the announcement earlier that month by Bitmover that they were withdrawing the free version of BitKeeper because of the development of SourcePuller.

BitKeeper had been used for the version control requirements of the Linux kernel project. Mackall decided to write a distributed version control system as a replacement for use with the Linux kernel. This project started a few days after the now well-known Git project was initiated by Linus Torvalds with similar aims.

The Linux kernel project decided to use Git rather than Mercurial, but Mercurial is now used by many other projects (see below).

In an answer on the Mercurial mailing list, Olivia Mackall explained how the name "Mercurial" was chosen:

Shortly before the first release, I read an article about the ongoing Bitkeeper debacle that described Larry McVoy as mercurial (in the sense of 'fickle'). Given the multiple meanings, the convenient abbreviation, and the good fit with my pre-existing naming scheme (see my email address), it clicked instantly. Mercurial is thus named in Larry's honor. I do not know if the same is true of Git.

High-profile projects such as the OpenJDK have used Mercurial in the past, though the OpenJDK no longer does as of Java 16.

Mercurial uses SHA-1 hashes to identify revisions. For repository access via a network, Mercurial uses an HTTP-based protocol that seeks to reduce round-trip requests, new connections, and data transferred. Mercurial can also work over SSH where the protocol is very similar to the HTTP-based protocol. By default it uses a 3-way merge before calling external merge tools.

Figure 1 shows some of the most important operations in Mercurial and their relations to Mercurial's concepts.

Although Mercurial was not selected to manage the Linux kernel sources, it has been adopted by several organizations, including Facebook, the W3C, and Mozilla. Facebook is using the Rust programming language to write Mononoke, a Mercurial server specifically designed to support large multi-project repositories.

In 2013, Facebook adopted Mercurial and began work on scaling it to handle their large, unified code repository.^[15]

Google also uses Mercurial client as a front-end on their cloud-based 'Piper' monorepo back-end.^[16]

Bitbucket announced that its web-based version control services would end support for Mercurial in June 2020 (then extended to July 2020),^[17] explaining that "less than 1% of new projects use it, and developer surveys indicated that 90% of developers use Git".^[18]

• Heptapod, a GitLab fork for Mercurial by Octobus
• Kallithea, a GPLv3 fork of RhodeCode
• Kiln by Fog Creek Software
• Phabricator by Phacility
• RhodeCode by RhodeCode Inc.

Source code hosting edit

The following websites provide free source code hosting for Mercurial repositories:

• Bitbucket by Atlassian (deprecated from February 2020; read-only since July 2020)^[18]
• Codebase^[19]
• FusionForge
• GNU Savannah by FSF
• Heptapod
• Mozdev
• OSDN^[20]
• Others^[21]
• Perforce^[22]
• Puszcza^[23] (a sister site to GNU Savannah, hosted in Ukraine)
• SourceForge
• SourceHut
• TuxFamily^[24]

Open source projects using Mercurial edit

Some projects using the Mercurial distributed RCS:^[25]

• Comparison of version-control software
• Distributed version control
• List of version-control software