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1290 posts · Page 92 of 108. ← Blog

Pratik Dhanave · ·8 min read

Web and CDN Caching

Every time a web page loads instantly on a repeat visit, or a video streams smoothly from halfway around the world, caching is the reason. The web is layered with caches — in your browser, at CDN edge servers near you, in front of origin servers — all applying the same caching principle to make the internet fast. And remarkably, much of it is coordinated by a few HTTP headers that let servers tell caches exactly what to store and for how long. Understanding web and CDN caching is understanding how the internet stays fast at global scale.

Every time a web page loads instantly on a repeat visit, or a video streams smoothly from across the world, caching is the reason. The web is layered with caches — browser, CDN edge, origin — all applying the same principle, much of it coordinated by a few HTTP headers.

Pratik Dhanave · ·9 min read

Distributed Caching

A cache inside a single application process is easy — but it doesn't scale, and every instance of your app has its own separate copy. The moment you run many application servers, you want a shared cache they all use, which means a cache that lives across the network on its own machines: a distributed cache like Redis or Memcached. This unlocks scale and sharing, but introduces the distributed-systems problems that a local cache never had. Understanding distributed caching is understanding how caching works at real scale.

A cache inside a single process is easy — but it doesn't scale, and every instance of your app has its own separate copy. Run many servers and you want a shared cache across the network on its own machines: a distributed cache like Redis or Memcached. This unlocks scale and sharing, but introduces distributed-systems problems.

Pratik Dhanave · ·8 min read

Caching Patterns

Knowing to cache is one thing; wiring the cache into your application correctly is another. Should the application manage the cache itself, or should the cache sit transparently in front of the source? Should writes go to the cache, the database, or both — and in what order? These questions have standard answers — the caching patterns — and choosing the right one shapes your consistency, performance, and complexity. Getting the pattern right is how caching goes from "store some stuff" to a coherent, correct design.

Knowing to cache is one thing; wiring the cache into your application correctly is another. Should the application manage the cache itself, or should it sit transparently in front of the source? Should writes go to the cache, the database, or both? These questions have standard answers — the caching patterns.

Pratik Dhanave · ·7 min read

What Cellular Automata Teach — Simple Rules and a Computational Universe

We began with a grid of cells flipping on and off by a trivial rule. We end with a radical idea: that the universe itself might be, at bottom, a vast computation running simple rules. This final post steps back to ask what cellular automata ultimately teach us — about complexity, computation, prediction, and the nature of reality — and why a toy of blinking cells turns out to carry some of the deepest ideas in science.

The big lessons: complexity needs no complex cause (emergence), computation is cheap and pervasive (Turing completeness) yet prediction has fundamental limits (irreducibility, undecidability), life's hallmarks emerge from rules, and — the boldest idea — the universe itself might be a vast computation running simple rules.

Pratik Dhanave · ·8 min read

Cache Invalidation

This is the hard one. "There are only two hard things in computer science: cache invalidation and naming things" names it directly — cache invalidation is genuinely, notoriously difficult. The moment you cache a copy of data, you've created a second source of truth that can drift from the first, and keeping them in sync (or deciding how much drift you'll tolerate) is a problem with no clean, universal solution. Understanding why it's hard, and the strategies for managing it, is the difference between caching that helps and caching that causes baffling bugs.

This is the hard one. 'There are only two hard things in computer science: cache invalidation and naming things' names it directly. The moment you cache a copy of data, you've created a second source of truth that can drift from the first, and keeping them in sync has no clean universal solution.

Pratik Dhanave · ·6 min read

Applications and Modeling — Cellular Automata in the Real World

Cellular automata are not only objects of theoretical fascination — they are a working scientific tool. Because local rules generating global behavior is exactly how much of nature operates, CAs model fluid flow, forest fires, crystal growth, traffic jams, biological patterns, and more. This post is about cellular automata as a modeling instrument: why they fit so many natural systems, where they are used, and what makes them powerful (and limited).

CAs are a genuine scientific instrument because nature is full of local interactions producing global behavior. How they model fluid dynamics (lattice gas/Boltzmann), crystal growth, biological patterns, forest fires and epidemics, and traffic jams — their strengths (simple, parallel, visual, emergent) and honest limits (discrete, sometimes ad hoc, qualitative).

Pratik Dhanave · ·8 min read

Eviction Policies

A cache is a small space pretending to be a big one, and the pretense only works if it's clever about what to keep. When a bounded cache fills up, every new item forces out an old one — and which one you evict determines your hit rate, which determines whether the cache is worth having at all. Eviction policies are the algorithms that make this choice, and understanding them (especially the workhorse, LRU) is essential to building caches that actually stay effective.

A cache is a small space pretending to be a big one, and the pretense only works if it's clever about what to keep. When a bounded cache fills up, every new item forces out an old one — and which one you evict determines your hit rate. Eviction policies are the algorithms that make this choice.