Tech Confronts Its Use of the Labels ‘Master’ and ‘Slave’

Companies and programmers are reexamining how technical terms are used amid Black Lives Matter protests. But some worry the changes are empty symbolism.

A few years ago, Karla Monterroso was at an airport when she noticed a glitch in a computer monitor that would normally display flight information. Instead, the screen showed the text “Master/Slave,” repeated at least 10 times from top to bottom. 

“I remember freaking out about it and going to [people working in] the terminal and letting them know that I thought that’s really inappropriate,” says Monterroso, CEO of Code 2040, a nonprofit dedicated to racial equality and inclusion in tech. “And they’re like, ‘No, that’s just the technology. That’s what the technology says.’”

The words “master” and “slave” have been widely used for decades in computing and other technical contexts, as a reference to situations where one process or entity controls another. Sometimes the metaphor is less precise: a “master” may simply lead, serve as a primary resource, or be considered first. Since 1976, the US has issued more than 67,000 patents using the terms, from an antenna system to a data encoding method to a “vehicle ramp assembly.”

Now, the Black Lives Matter movement is prompting renewed scrutiny of diversity and equity in tech—including its vocabulary.

Microsoft’s GitHub, a popular software development platform with 50 million users, will replace the word “master” as the default branch name for new repositories, a spokesperson says. GitHub is also making it easy for users to choose their own default branch name when creating a new repository, and releasing guidance to rename existing ones, the spokesperson says. There’s never been a complementary use of “slave” in GitHub’s repository architecture.

There are also discussions about changing the use of “master” within Git, the open-source project that’s the foundation of GitHub, says Christian Couder, a Paris-based member of the Git Project Leadership Committee. A Git repository stores the revision history for a set of files, such as source code for a software project. The default name for the main thread of that history has been “master.” In an email, the committee said it recently modified the code so users could set their own preferred default branch name.

As more organizations reexamine their language, coders are engaging in intense debates about the extent to which these words matter. If there is no “slave,” does “master” need to go? Are movements to change such words meaningful when so much else needs to be done to increase diversity, equity, and inclusion in the tech world?

Dwayne Slater, a developer in San Jose, is one of more than 3,000 people who signed a petition opposing GitHub dropping the word “master.” The petition calls such moves “distractions, not solutions,” and says it “creates confusion and unnecessary work for developers.” Slater, who is Black, wrote in the comments, “To see GitHub use the color of my skin to make meaningless change is a slap in the face. There are more useful causes to bring to attention, words are not the issue, police brutality in the United States is the issue.”

In an interview, Slater says he supports replacing the word “slave” where it’s still used. But on GitHub, Slater is fine with “master” because he thought of it in the sense of a “master copy” or “mastering a craft” during more than six years of using Git.

Stephen Stafford, a developer in San Diego, says reading the news about GitHub changing the term “master” was “an uncomfortable experience” for him, since he didn’t view it as a problem. Stafford, who is also Black, likened the move to the “performative activism” of Blackout Tuesday, in which people posted black squares on social media without necessarily doing anything else for the Black Lives Matter cause.

“To see GitHub use the color of my skin to make meaningless change is a slap in the face. There are more useful causes to bring to attention.”

Dwayne Slater, a developer opposed to GitHub’s decision to drop “master”

But Caroline Karanja in Minneapolis sees updating these terms as an important piece of the effort to create more inclusive spaces in tech. She is the founder of 26 Letters and the CEO of Hack the Gap, two organizations aimed at equity and inclusion in tech. When she was teaching herself to code, she thought the choice of the words “master” and “slave” was both odd and specific. ”This didn’t have to be the language that we used,” says Karanja, who is Black. While learning Git, she remembers struggling to figure out how to change the default “master,” and supports giving users an easy way to do so.

The “master/slave” metaphor in technology dates back to at least 1904, describing a sidereal clock system at an observatory in Cape Town, according to a 2007 essay by Ron Eglash, a professor at the University of Michigan. The words may have been chosen to emphasize the innovation, Eglash wrote: “The concept of a free master that did no work and a slave that followed the master’s orders made for a vivid, if ethically suspect, technosocial metaphor.”

In the 21st century, the language is increasingly questioned. Eglash and others point to a 2003 memo from the Los Angeles County Office of Affirmative Action Compliance, responding to an employee’s complaint about using “master” and “slave” in computer contexts. The county agency declared the words “not an acceptable identification label,” Eglash wrote, which incited debate in the pre-Twitter internet era.

Other organizations have more recently revised language that could be seen as rooted in racism. The Django web development platform changed “master” and “slave” to “leader” and “follower” in 2014, and the open-source content-management system Drupal went with “primary” and “replica” the same year. The Python programming language dropped both “master” and “slave” in 2018, which also generated some controversy among users.

In 2019, an employee of San Francisco software company PagerDuty suggested replacing “slave” with “replica” in code used internally at the company; PagerDuty made the change. The company now “encourages the use of ‘replica,’ ‘standby,’ ‘secondary,’ or ‘follower’ instead of ‘slave’ in code and in conversations, as well as ‘deny/allow’ lists rather than ‘blacklists’ and ‘whitelists,’” a spokesperson says.

Last month, on Juneteenth—June 19—the data management company Delphix hosted a hackathon for employees to make coding terminology at the company more inclusive. Engineers tailored replacements for “master/slave” to specific contexts, says Sebastien Roy, the company’s director of systems platform development. Alternatives included “active/standby,” “writer/reader,” “parent/child,” and “leader/follower.” A reference to “blacklist” was changed to “list of removed faults.” In another case, they left “black box” alone because they decided it doesn’t have negative connotations, Roy says.

The petition opposing GitHub’s move away from “master” says the same logic argues for renaming “master’s degrees, master bedrooms, master gardeners, puppetmasters, and so on.” Some of that is already happening: Recently the Houston Association of Realtors decided to stop using “master” to refer to bedrooms and bathrooms in its property database.

When Petr Baudis chose the word “master” for the main Git reference in 2005, he was thinking of the word as he would a “master recording.” The then-20-year-old Czech student and non-native English speaker thought the word sounded nice, although in retrospect he wishes that he had chosen “main.”

Git has its origins in supporting Linux kernel development, which still uses the words “master” and “slave.” Linus Torvalds, lead developer of the Linux kernel, created Git to replace the proprietary software BitKeeper, which used the same terminology. 

Baudis, now chief technology officer of the startup Rossum, doesn’t remember referencing that history when he came up with “master.” He also doesn’t remember any conversations about the historical uses of the terms. Baudis says he and many coders live outside the US and aren’t familiar with American connotations of the words. “When you say ‘master’ or ‘slave,’ it doesn’t evoke the concept from, I don’t know, history books or even contemporary reality, but it mainly evokes those purely technical meanings,” he says.

Many participants in Code 2040’s programs, which include fellowships for Black and Latinx college and graduate students in the tech sector, have said the terminology makes them uncomfortable, Monterroso says.

“When they have pushed back the response has been, like, ‘Oh, this isn’t about racism, just technical terms,’ without the emotional intelligence to see that using those terms as technical terms has definitively racial-traumatizing impacts on people,” she says.

The master/slave language is far from the only thing that makes coders of color feel unwelcome or out of place. Like the way, when Karanja wore a high bun in a previous job, a colleague would always squeeze her hair. Like how Stafford feels like he needs to hide his Southern accent at work. Like how PagerDuty software engineer Aliyah Owens, in computer science classes where she was often the only Black woman, was sometimes asked, “Do you belong here? Oh, I thought you were another major.”

And then there are big things. When Gloria Washington was a doctoral student at George Washington University, her adviser excluded her from meetings and made her feel like he didn’t believe in her. She had already spent four years in the program when the adviser told her she was not “not research or analytically capable” of completing her PhD.

“After he told me that, I’m not going to lie, I questioned everything about myself,” she says.

But after about six weeks of self-doubt, Washington decided she would not allow one person to determine her success. She found another adviser and finished the degree. Her first adviser “had to end up shaking my hand as Dr. Washington,” she says.

Now, as assistant professor of computer science at Howard University, Washington says the master/slave terminology reflects how systemic racism was “built into the fabric of computer science.” She supports changing the terms, but considers these gestures purely symbolic if tech companies do not appoint diverse people, particularly Blacks, to leadership positions—positions beyond serving as “the faces of diversity and inclusion.”

“They can, I guess, make little donations and little tokens of change, like changing a name or whatever,” Washington says. “But at the end of the day, it doesn’t translate to real money being invested in the Black community, and until that happens, that is when real change will happen.”

All Rights Reserved for Elizabeth Landau

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