Performance analysis tool which makes it easy to use Intel Processor Trace to visualize every function call made leading up to an event of interest with nanosecond precision. I designed and implemented this (along with an intern I mentored) for Jane Street, where it’s been incredibly successful internally, and wrote a…
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During my final term at UWaterloo I took the CS444 compilers class with a project to write a compiler from a substantial subset of Java to x86, in teams of up to three people with a language of the group’s choice. This was a rare opportunity to compare implementations of large programs that all did the same thing…
One day a coworker mentioned that he was thinking about APIs for distributed compute clusters and I jokingly responded “clearly the ideal API would be simply calling telefork() and your process wakes up on every machine of the cluster with the return value being the instance ID”. I ended up captivated by this idea: I…
This afternoon I spent some time with the free trial of the Hopper Disassembler looking through the binary of Sublime Text 3. I found some interesting things and some undocumented settings.
Ever wanted more different ways to understand what’s going on in a program? Here I catalogue a huge variety of tracing methods you can use for varying types of problems. Tracing has been such a long-standing interest (and job) of mine that some of these will novel and interesting to anyone who reads this. I’ll…
Something I’ve been thinking about recently is how when I’ve worked on any kind of distributed system, including systems as simple as a web app with frontend and backend code, probably upwards of 80% of my time is spent on things I wouldn’t need to do if it weren’t distributed. I came up with the following description…
During my internship at Jane Street 1 , one of my projects was a config editing tool that at first sounded straightforward but culminated in me designing a custom tree diffing algorithm using dynamic programming, relentlessly optimizing it and then transforming it into an A* accelerated path finding algorithm. This…
In the course of trying to figure out how to smoothly zoom timelines of a billion trace events, I figured out a cool tree structure that I can’t find elsewhere online, which it turned out two of my friends have independently derived after not finding anything on their own searches. It’s a way of implementing an index…
One reason to know how your data structures work is so that when your problem has unusual constraints you can tweak how they work to fit the problem better or work faster. In this article I’ll talk about four different fun tweaks to the concept of a hash table that I made in the process of using hash tables to…
Edit 2017/12/10: So I screwed up, I thought I was safe confirming it in two different ways but I was using an external monitor and all of the below is accurate only for a specific multi-monitor case. Skip to the bottom to read about my new results.