Thumbtack Engineering Engineering

Dependency injection... for performance?

We recently added automatic dependency injection to the PHP codebase powering our website. As we’ve said in the past, dependency injection is a good move for a lot of reasons. It leads to clearer, easier to understand code that is more honest about what it depends upon. Automatic dependency injection reduces boilerplate code to construct objects. And of course, it makes code easier to test.

But it had another benefit we weren't expecting. It made our pages load a few milliseconds faster.


Some of our dependencies are slow to construct because they need to read a settings file or because they use a library that instantiates a ton of objects. Our dependency injection framework allows dependencies to be constructed lazily, which (for most requests) means never constructing them at all. Better, faster code — what's not to love?

Ready to try out dependency injection for yourself? We made our library, ttinjector, public for all to use.

Welcome Mark Schaaf

Mark Schaaf
Mark hiking the John Muir Trail

We're excited to introduce Mark Schaaf, the newest member of our team.

Mark is joining us as Thumbtack's VP of Engineering. He previously was a Senior Engineering Director at Google, where he ran the mobile display ads engineering team and later led consumer and merchant payments engineering. Previously, he was the 2nd engineering hire and Senior Director of Engineering at AdMob, which was acquired by Google in 2010.

In his free time Mark tells us that he likes to get outside, hiking and backpacking the Sierra Nevada. Whenever the weather cooperates, he enjoys snowcamping.

Welcome, Mark!

Interviewing for Female Friendliness: Tips from an Engineer

There have been countless articles written recently about “Women in Tech”. Yet, when I think back to the month I spent interviewing before deciding to join Thumbtack, I don’t remember being at all concerned about vetting any of those companies for female-friendliness. Luckily, I ended up in a great environment, but I know other women who haven’t been so fortunate. That got me thinking about some questions that perhaps I should have asked upfront to ensure that I was making the right culture fit.

Questions About Work

Ask This: How often do people ask questions? How do people ask questions?

The right answer to this question should be “all the time.” Women, as compared to men, tend to suffer more from impostor syndrome. We believe that our success is a result of luck, timing, or deception rather than our own intelligence or competence. This can make it difficult for us to ask for help, for fear of being discovered to be an imposter. It is easier to ask for help when a supportive and humble culture is already established, where engineers are constantly asking for and receiving help from each other.

Ask This: What practices do you have in place to ensure high quality code and continued learning?

Processes for reviewing code and a culture of continued learning can be additional indicators of humility.

Specifically, look for engineering teams that:

  • Pair program: It doesn’t have to be required or happen all the time, but teams whose engineers pair with each other even a couple of times a week are likely to be teams who value collaboration. Because engineering can sometimes be an isolating profession for women, this type of collaborative environment can be great for female engineers.
  • Participate in code review: A great follow-up question here is “Why are code reviews valuable to you?” Bonus points go to the company whose engineer responds that not only do code reviews help ensure high quality code in the codebase, but they also create more opportunities for engineers to learn from each other and learn about different parts of the codebase.
  • Take online classes together, read, provide an education stipend: A culture where engineers are continually learning can help women rid themselves of imposter syndrome by reminding us that everyone is still learning and no one knows everything.

Additionally, pay attention to the tone with which your interviewer speaks about these topics. If a company encourages pair programming, but your interviewer doesn’t recognize the benefits, this is a red flag.

Questions About People

Ask This: Are there any women on the team? If so, what positions do they hold?

If the answer is no, it isn’t necessarily a red flag. Many teams want to hire more women, but there aren’t enough of us out there. In this case, you could follow up with “Is it important to you to have a diverse team? Why or why not?”

If the answer is yes, however, you have a great opportunity to speak with someone directly about what it’s like to be a female engineer at that company. Ask for their contact information so you can reach out to them if you don’t meet them during your interview. By the way, if you’re interviewing here at Thumbtack, I’d love to meet you!

Ask This: Are any engineers involved in programs aimed at supporting women in the industry? (e.g. PyLadies, Women Who Code, Hackbright, etc.)

I found out about Thumbtack because three of the nine engineers on the team (at the time I was hired) had volunteered at Hackbright, an organization that provides engineering fellowships for women. This indicated to me that Thumbtack cares about hiring more women in engineering roles.

Questions About Culture

Ask This: What kinds of things do team members do together besides work? How central is drinking to social events?

A female friend of mine recently asked this question at a company where she interviewed for a software engineering position. The response? It was something like this:

“We do a lot of things outside of work together. I actually went surfing with one of my coworkers this morning. But if you wanted to find someone to, I don’t know, go shopping with you, I’m sure you could.”

Because, you know, all women love shopping. Such gender-based assumptions would cause me to worry about future assumptions that might be made. Not all answers will give such a clear signal, but any answer should still give you a good feel for the personalities of the people you would be working with.

This question can also suss out how central drinking is to social events. I’m not saying that women don’t like drinking, but team bonding that is centered around drinking can be an indicator of a “brogrammer” culture. Here we brew beer and take mixology classes together, but even when we do those things the focus is not on consuming excessive amounts of alcohol. Rather, we do these things to learn something new, appreciate the drinks, and get to know each other better.

Besides being an indicator for culture, excessive drinking can lead to uncomfortable situations for women as inhibitions are lowered and teammates say or do things they might not have otherwise.

In Conclusion

I feel very grateful to have found a workplace that has such a fantastic culture and lacks many of the issues female developers face. Many thanks to the engineers on our team that have worked so hard to build this culture. I hope this post will help women who are currently looking for a job in software engineering, or who might be looking in the future. If you are currently looking, you might also want to check out the interview prep events hosted by Women Who Code, as well as posts like “Self Care Strategies for the Software Engineer Job Search” on the Hackbright Academy blog. Feel free to share some of the resources you use in the comments!

Brett Cannon - Python 3: Why you want it and how to (eventually) get it

From the October 14, 2014 SoMa Tech Talk series.

We were happy to host Brett Cannon for his talk "Python 3: Why you want it and how to (eventually) get it."

Brett has been a core Python contributor since 2003 and recently undertook rewriting the Python import system for Python 3. He's a big advocate for encouraging developers switch to Python 3 and has inspired us here at Thumbtack where we have been using it successfully in production for a number of months.

In this talk, Brett walks you through why you should really want to switch, some of the benefits you can get right now, even on Python 2.7, and what next steps you can work on right now to prepare yourself to switch.

Evolution of Thumbtack’s product process

As every product team knows, designing a good product process is hard. As the team grows and business strategies change, the dynamics of a product team change, and processes must evolve to fit the new normal. At Thumbtack, we review our process together as a team once every quarter and deliberate together how the process should evolve. It’s a day long activity that has resulted in significant shifts in process over the years-- from focus teams, to 2 week sprints, to task-based systems, to teams. And thus far, it, along with great home-cooked food, has been critical in ensuring a growing team of happy engineers, designers, and product managers.

What is the process optimizing for?

We treat our product process like a product and iterate on it in order to find the process that best meets its objectives within a set of constraints. We’ve found that the product process has two major constraints: the size of the team, and the type of business priorities at the time -- how many, timelines, and whether they were more execution or experimental. In additional for these two satisfying these two constraints, we believed the product process should:

  • Foster individual ownership and promote excitement about work
  • Be effective against meeting company goals
  • Disseminate knowledge and context effectively
  • Support day-to-day needs of the company (e.g., emergency problems, engineering requests from other functions)
  • Maximize time spent working toward goals and minimize overhead
  • Ensure high quality software and design across the product
  • Scale as the team grows (This came later).

How does the product process get changed?

As a product team, we hold a Product Process Review meeting (PPR) at a regular interval to discuss the process, and any changes to the process agreed upon during the meeting is carried out until the next PPR. The inaugral meetings was due to a disagreement within the company early on about how the product process should be. But since then, it has been invaluable to improving the process and maintaining morale.

The review meeting is held at regular intervals (every 6 weeks and later on, every quarter). The entire product team (engineers, designers, product managers) meets and often dedicates an entire day to the discussions and decisions. First, we reflect together on what went well, and what could be better. Each person is expected to offer an opinion and all comments are written down. Then, we group the #couldbebetters into main topics, and break up in to cross-functional teams to discuss potential solutions. These discussions usually take an hour or two, and may go for much longer if there’s heated debate. Finally, we regroup as a team for each topic, discuss different solutions, do a majority vote, and make a decision. If a particular decision is a close call, then we’ll flag it to be revisited explicitly in the next PPR. This entire process is documented and sent to the entire company to keep everyone else up to date.

The early years: waterfall

In the very early years of the company, we had a waterfall process between engineering and design. Most design-heavy projects went from UX wireframing to visual designer to markup to an engineer 6 weeks later. There was no formal design review process, and projects that involved design were done by engineers with minimal involvement from design. The engineer would feel no ownership of the product, and find many issues with building it effectively. This bred discontent. Startups galore have realized that waterfall does not work, particularly in this early stage of the company where the focus was on quick experimentation and ownership. We scratched that process very quickly, and I will not dwell upon well-known reasons of why waterfall doesn’t work here.

Focus and iterate: focus teams

Focus team formed as a way to quickly experiment and iterate around certain objectives. As its name implies, it optimized for focus. Thumbtack was still in its youth and needed to find product-market fit. We had 8 engineers and 2 designers, and each team was responsible for one company initiative critical to the company's survival: "find a monetization strategy", "increase request volume" or "get customers to hire".

What worked well

This structure was very effective for focus and coordination around a particular goal and getting things done. Many, many experiments were ran and Thumbtack iterated into a model that led to our current growth trajectory as a company Everyone felt great ownership over what they were working on and were involved in the ideation to implementation process.

What didn't work

  • Nothing outside the focus of the focus teams got done.
  • The objectives were so massive that these teams went on and on, sometimes for more than 1 year. * The engineers overwhelmingly felt "stuck" and that they had to develop such deep expertise in an area that they could not move to another product area.
  • Setting objectives were ambiguous. The process of determining what the focus teams worked on felt top-down, and stifled ideas from the rest of the company

One team, two week sprints

After finding product-market fit, the company’s priorities shifted to growing the current model. The product team decided it was a good time to move out of focus teams and to a process that lets engineers have more fluidity between projects and autonomy for anyone in the company to propose new projects. The outcome was 2 week sprints.

General setup

  • Each sprint started on a Tuesday (so engineers didn't have to rush to push code Friday evenings).There was a retrospective in the morning where everyone would state what they intended to accomplish, and what was accomplished (this adds accountability). And then everyone would then either continue projects or pick up new projects, and kick-off meetings were held Tuesday afternoon.
  • We tracked progress in Trello cards. There were 4 columns: Prioritized, In Progress, Not Doing, and Finished (with the week it was finished in) and each person would put his/her face on a card when it's picked up. This was a great way to share who was working on what. There were separate Trello boards to track bugs, small polishes, and project ideas / pipeline. A bug would only be picked up if it was urgent (and we defined urgent as blocking the core the requesting or quoting process), else it was simply tracked. We then did bug and polish weeks with the entire team every quarter.
  • PMs or anyone else on the team could write project proposals for features or infrastructure related work . These proposals covered the goal, why it’s important, details, resources, alternatives.
  • PMs, along with 1 engineer and 1 designer met weekly to discuss and prioritize projects. In the in between weeks, the meeting were more for looking at higher level data, discussing upcoming features, and triaging bugs and emergencies. Anyone was welcome to join the prioritization meetings (or any meeting really), and was especially encouraged if they had a project they wanted to work on. Notes from meetings are sent to a general mailing list everyone is encouraged to subscribe to.

What worked well

  • There was clear visibility and accountability of who is working on what. The entire team would at the Tuesday retrospectives to collectively discuss progress and learnings from their projects.
  • Process mandated substantive project proposals with specific details on why and how a feature will be built. This meant in depth thinking went into each proposal.
  • It was flexible and the team was able to shift priorities much more quickly
  • Lightweight with few overhead meetings during sprints
  • Team members no longer "stuck" on a project. Instead, they had the option to move on to a different project every 2 weeks.

What didn’t work

  • There was not enough time to think about the next cycle's work or to estimate the complexity and time properly. Engineers began to feel like because they didn't have time to think about the project proposals, they simply "got put on" new projects
  • Design doesn't work well within 2 week boundaries nor does it sync well with project timelines
  • Quick deadlines force a focus on getting things out rather than on quality. In addition, prioritizing infrastructure projects along side product projects was difficult and given there was not a infrastructure focused team at the time, eng infrastructure suffered (and we paid for it many times over later).
  • With everyone working across the product and the opportunity to switch every two weeks, sharing context and knowledge needed for a particular project got much harder. In addition, given desires to move on, often projects were left unfinished or unpolished. There was then no process to continue them.

Onwards towards tasks!

After trying out the 2 week sprints for 4 months, we felt that it was too long for certain projects, and too short for others. There were lots of "several day" projects that was awkwardly tossed around and then informally done. And so, the team decided to try a task based system to accommodate these smaller tasks.

General setup

  • Projects were broken down into small tasks that are estimated to take one day. Prioritization of tasks happened on a weekly basis based on historical velocity by a PM and lead eng, but work was not broken into cycles and progressed continuously.
  • Engineers were expected to pick up cards as they finish previous ones, and could “claim” a set of cards if they belonged to one project.
  • We continued using Trello to track these tasks as Prioritized, In Progress, Not Doing, or Finished. We also had tags for cards/tasks that were added mid-week for any reason Bugs and polish processes were kept the same.

What worked well

  • Accommodated smaller tasks being done
  • Forced scoping of projects down to small tasks, which forced more detailed planning and time estimation upfront. There were often cards added just for scoping.
  • We realized that there are many tasks (as much as 50% of all cards) come up mid-week. We didn’t fully appreciate this before this process.

What didn’t work

  • No ownership or accountability at a project level for engineers, which resulted in us not being able to effectively hit company goals
  • In a world with no project proposals or ownership at a project level, there was essentially very little context on why a task needed to be done, and very little motivation to get it done.
  • Projects were broken up and one part (likely the easiest or most interesting part) would be implement but not another.
  • Time estimations were rarely accurate, and hence while there was an expectation that we finish what was prioritized the previous week, this rarely happened in practice.
  • Design was very difficult within this process. Essentially, it did not work in this process at all.

Breaking into teams

The task-based system got messy quick, and it was our shortest-lived process after waterfall. The team meanwhile raised another round of funding and was poised to grow dramatically in the following months. It was clear that our 20 person product team will soon be (if not already) too big to operate as a single team. It was increasingly difficult to share knowledge, hold each other accountable, or simply fit into one meeting room. And so, we moved back to the one scalable solution: Product teams.

General setup

  • Product teams were given a mandate for one quarter and were in sync with the company’s quarterly planning process. Team objectives were set by the company leadership with heavy input from the teams and staffed accordingly. In Thumbtack’s case, we had Infrastructure, Mobile, and 2 product-focused teams.
  • Engineers gave preferences to which team they’d like to be on, and the engineering managers got together to staff the teams based on preference, need, skillset, and seniority. (We tried but scraped a pure lottery system first where engineers were randomly assigned numbers and teams were filled based on 1st preferences in order of numbers). Engineers were given tokens if they did not get a 1st choice so they had priority next quarter.
  • Engineers are expected to switch teams each quarter to avoid being stuck on teams for too long.
  • Each team were given the freedom to choose tools, metrics, and processes as they saw fit.

What worked well

  • There was strong accountability and ownership within teams. However, some teams had members constantly switching in and out (interns, new hires), and these shifts clearly shifted both the dynamics of the teams and the level of ownership
  • Teams were empowered to adapt and change priorities as needed
  • New engineers had a smaller group to work within and bond with.
  • Pairing happened more than ever with teams, both within and across teams
  • Designers finally fit into this process well and could work alongside engineers and PMs as a part of a coherent team.

What didn't work

  • Cross-team sharing and syncing did not happen as often as needed since each team was on different tracking tools. The team leads also did not sync as formally as needed
  • Scoping upfront was important to the notification within teams. Teams that were too broadly scoped lacked accountability and focus. Teams that were under-staffed were unable to meet its goals no matter how hard the team worked
  • The things that fell outside of the teams’ scopes were hard to pick up.

In general, teams worked well for the growing size. We made some small improvements after one quarter. We focused on scoping the teams better and explicitly assigning team leads for each team. We also learned that cross-team communication does not happen naturally, so we put meetings in place for team leads sync and time during team meetings to share among the team, and all got on the same tracking tool.

Overarching themes across product processes

Across these four iterations, we learn much about what works and what doesn’t work for us. There is no one-size fit all solution, and the best process depends on the size and business priorities at the time. Here, however, are some things we found consistently worked and did not work:

What we love and know works

  • Aztec process for dealing with smaller day-to-day needs of other parts of the org: one engineer would be designated the Aztec for a week and everyone would send their requests to a dedicated email that the Aztec monitored. If it was a small task, the Aztec would just do it. If it was a larger request, it would be tracked and picked up when appropriate (e.g. next quarter, during bug or polish week, etc)
  • Having a dedicated bug squashing + polish week every quarter where we as a team get through as many small changes as possible to polish and clean up the existing product. There are typically small 1/2 day to 1 day tasks, and can be clearly laid out on a Trello card.
  • Design and engineering building and iterating together: any process that promoted engineers and designers to work more closely together resulted in better product.
  • Having a product process review process to change process as needed: critical to a growing team!

What we haven’t figured out

  • Time estimations are inaccurate as complexity is hard to understand prior to starting and we consistently under-estimate how much time recruiting and small interruptions from rest of the company takes.
  • Lack of formal QA process. Quality relied on Engineers and PMs (and often CS) running manual tests and building unit tests. As the company scaled, this got harder and more bugs started being introduced.
  • No good way to store all the knowledge across teams and keeping the rest of the company up to date. There is a constant battle on sharing and disseminating context that gets exponentially harder as the company grows. Thumbtack to date hasn’t tried set release date or formal release notes, but perhaps in the near future, we’ll be at a size where that is valuable.

That is where Thumbtack is in its current product process. As we grow our product team, we’ll have much more to learn in terms of how teams are best run and how they stay in sync across the company. Is the a different process for infrastructure teams vs product teams? Will we have different processes for building known features (e.g. reaching parity with web on Android) versus experimenting with new features? How can we stay better in sync with the rest of the business and their needs? What channels of communication will we have?

Interested in joining us? Find out what it's like to work at Thumbtack!

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