The accepted answer is boring but all other answers are very creative and informative.

Event Loop is a leak abstraction. It forces us to understand is characters to write well perform applications. It’s the primary primitive browser that allows writing code that won’t cause blocking behaviour. Callbacks, Promises and Async/Await is how to deal with event loop.

FixedArray and FixedDoubleArray are used to create objects in JavaScript, and although the new implementations looked valid at first glance, they were missing a key component: a maximum length check to ensure that the newly created array’s length cannot not go past a predefined upper limit. To the untrained eye, this bug does not look exploitable, but as shown on the bug report, Sergey made use of TurboFan’s typer to gain access to a very powerful exploitation primitive: an array whose length field is much larger than its capacity. This primitive provides an attacker with an out-of-bounds access primitive on the V8 heap, which can very easily lead to code execution

The percentile calculations were taking about 6 minutes instead of the required 30 second SLA. How and which tools we can use to debug and reduce that to the target SLA: 30 seconds

HOT stand for “Heap Only Tuple”. It is a feature that overcomes some of the inefficiencies of how PostgreSQL handles UPDATEs. Update adds a new row version call tuple. In other words, an update is like delete followed by an insert. Essentially, UPDATE-heavy workloads are challenging for PostgreSQL. This is the area where HOT updates help.

Using some high school level statistics and a fair knowledge of SQL, I implemented a simple anomaly detection system that works

Show what makes a test a good one and describe desired and unwanted properties. Interestingly enough, all those properties hold, no matter how isolated or integrated the test is

Network is the backbone of almost any cloud application. When companies scale, we add more network, qa, staging, prod, support, rds, elasticache. Eventually we need to allow those network to communicate with each others. How to manage that complexity? Adding a new network and allow traffic flow require you to add a new route table. A single bad route can cause lost traffic? Let’s learn how Slack manage that complexity

You cannot secure your wifi network without knowing about attack vectors. How will you validate that your netowrk is secure? You need to know some tools for hacking purposes.

This is in Golang code sample but you get the idea of building an inverted index, text analysis, tokenizer, filter and the trick to drop stop words - because almost anything in English contains them(such as them, I, you, etc)

The quickest way to allow SSH access is adding their public key to authorized_keys, which obviously won’t scale. In this, we looked at how we setup a CA as a centralization auth method for SSH