Very casual whiteboard type chat sessions on a regular basis in SF, NYC, Redwood Shores, Mountain View, and Atlanta. Stop by!
Also check out the meetup users groups in lots of other cities.
How Journaling and Replication Interact
Version 1.8 of MongoDB supports journaling in the storage engine for crash safety and fast recovery. An interesting question arises then regarding how journaling interacts with replication. A traditional approach might be to wait for the commit (i.e., journal physical write confirmed) before replicating any data. MongoDB does not do this. Instead, it allows data to replicate even if the journal write has yet to occur or be confirmed. We then must ask “but what happens if we crash before journaling but the data replicated out?” With replica sets , it turns out this is ok. In a replica set the rule is that the freshest node will be elected primary. Thus if the crashed node comes back up, but the node which received the unjournaled data is ahead, it will be primary. We might then ask about a cascade of failures. This is ok too as replica sets have a notion of rolling back to a consistent point of view. How do we know our data won’t be rolled back? The answer is that a write is truly committed in a replica set when it has been written at a majority of set members. We can confirm this with the getLastError command. For example, if our write has made it to the journal on two out of three total set members, we know the data is committed even if nodes fail in a cascading sequence, and even if a minority of nodes are permanently lost. Why bother replicating so quickly? It lets us minimize latency between secondaries and primaries. In addition more writes will be successful than traditionally when a crash occurs. Yet the latency reduction is the biggest advantage: fsyncing to disks can be slow – replication lag (if on a LAN) can be less than the time to fsync to disk. Plus both can then be underway concurrently.
The Rise of the Strategic Developer
The work of developers is sometimes seen as tactical in nature. In other words, developers are not often asked to produce strategy. Rather, they are expected to execute against strategy, manifesting digital experiences that are defined by the “business.” But that is changing. With the automation of many time-consuming tasks -- from database administration to coding itself -- developers are now able to spend more time on higher value work, like understanding market needs or identifying strategic problems to solve. And just as the value of their work increases, so too does the value of their opinions. As a result, many developers are evolving, from coders with their heads-down in the corporate trenches to highly strategic visionaries of the digital experiences that define brands. “I think the very definition of ‘developer’ is expanding,” says Stephen “Stennie” Steneker, an engineering manager on the Developer Relations team at MongoDB. “It’s not just programmers anymore. It’s anyone who builds something.” Stennie notes that the learning curve needed to build something is flattening. Fast. He points to an emerging category of low code tools like Zapier, which allows people to stitch web apps together without having to write scripts or set up APIs. “People with no formal software engineering experience can build complex automated workflows to solve business problems. That’s a strategic developer.” Many other traditional developer tasks are being automated as well. At MongoDB, for example, we pride ourselves on removing the most time-consuming, low-value work of database administration. And of course, services like GitHub Copilot are automating the act of coding itself. So what does this all mean for developers? A few things: First, move to higher ground. In describing one of the potential outcomes of GitHub Copilot, Microsoft CTO Kevin Scott said, ““It may very well be one of those things that makes programming itself more approachable.” When the barriers to entry for a particular line of work start falling, standing still is not an option. It’s time to up your strategic game by offering insight and suggestions on new digital experiences that advance the objectives of the business. Second, accept more responsibility. A strategic developer is someone who can conceive, articulate, and execute an idea. That also means you are accountable for the success or failure of that idea. And as Stennie reminded me, “There are more ways than ever before to measure the success of a developer’s work.” And third, never stop skilling. Developers with narrow or limited skill sets will never add strategic value, and they will always be vulnerable to replacement. Like software itself, developers need to constantly evolve and improve, expanding both hard and soft skills. How do you see the role of the developer evolving? Any advice for those that aspire to more strategic roles within their organizations? Reach out and let me know what you think at @MarkLovesTech .