The Runtime Theory

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Articles

Every article starts from the same place: trace the system, understand the tradeoff, write down what actually happens. New dispatches are published continuously.

networking

What Happens When You Call an API?

One request, traced end to end: DNS, TCP, TLS, HTTP, load balancing, server logic, and the database — with the real cost of every hop.

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Index

By topic

  1. software architectureThe Law of Demeter in PracticeMessage chains, the law of diminishing knowledge, and why 'don't talk to strangers' prevents the most brittle code you'll ever write.
  2. cloudContainers Aren't Lightweight VMsNamespaces, cgroups, seccomp, and the real isolation boundaries — what containers actually isolate and what they don't.
  3. backendConnection Pools Aren't FreePool sizing, exhaustion, idle connections, and the hidden queue — why 'just add a pool' is incomplete advice.
  4. networkingHow HTTP/2 and HTTP/3 Change EverythingMultiplexing, server push, and QUIC — why keep-alive is the old answer and what the new protocols actually fix.
  5. databasesWhy Your Query Is Slow (And It's Not the Index)Buffer pool misses, WAL contention, lock waits, and connection pooling — the non-index causes of database slowness.
  6. operating systemsWhat Really Happens During a System CallTrap, ring transition, and the syscall table — the cost of asking the kernel for help and why it's never free.
  7. operating systemsHow Virtual Memory WorksPage tables, TLB, and demand paging — why your 16GB laptop 'has' 128GB of addressable memory.
  8. distributed systemsEventual Consistency Is a SpectrumStrong, causal, read-your-writes — the consistency zoo and when each model is the right engineering choice.
  9. distributed systemsWhy Distributed Systems Are HardThe CAP theorem's real meaning, partial failures, and the eight fallacies — why networked code is a different discipline.
  10. distributed systemsConsensus Algorithms Aren't About AgreementRaft, leader election, and split-brain — what consensus actually solves and what it doesn't.
  11. databasesHow SQL Query Optimizers ThinkCost-based optimization, join ordering, and statistics — why your query plan changed overnight and what to do about it.
  12. algorithmsHash Tables Aren't MagicLoad factors, collision strategies, and cache misses — why O(1) has a constant that bites when you least expect it.
  13. runtimeJIT Compilation: Why Hot Loops Become Machine CodeTiered compilation, on-stack replacement, and deoptimization — when the runtime outperforms the ahead-of-time compiler.
  14. distributed systemsWhat Is a Distributed System, Really?A system where the failure of a computer you didn't even know existed can render your own computer unusable. How to recognize a distributed system you never asked for.
  15. runtimeWhat Happens When You Allocate an ObjectThread-local allocators, TLABs, bump allocation, and why object allocation is nearly free until the moment it isn't.
  16. runtimeHow Garbage Collectors Decide What to FreeMark-sweep, generational hypothesis, and GC pauses — the physics of automatic memory management and why it's never truly free.
  17. algorithmsBig-O Measures Scaling, Not SpeedO(n) says nothing about how fast your code is today — it predicts how it behaves as the input grows. What complexity analysis is really for, and when it misleads.
  18. networkingWhat Happens When You Call an API?One request, traced end to end: DNS, TCP, TLS, HTTP, load balancing, server logic, and the database — with the real cost of every hop.
  19. cloudServerless Is Still a ServerThere is no code without a machine, a kernel, and a cold start. What serverless actually automates, and where the abstraction leaks.
  20. runtimeHow a Function Call Really WorksStack frames, registers, calling conventions, and tail calls — what the machine does between the opening brace and the first line of your function.
  21. system designA Load Balancer Is Not a Magic BoxLayer 4 vs layer 7, hashing vs health checks, stickiness, and the failure modes hiding behind the most over-trusted building block in web infrastructure.
  22. backendLatency Numbers Every Engineer Should KnowA working model of time on modern hardware: the real cost of a cache miss, a syscall, a network hop, and a disk read — and why these numbers are the vocabulary of systems thinking.
  23. databasesThe Anatomy of a Database TransactionACID is a slogan; the write-ahead log is the mechanism. How a transaction commits, why the WAL exists, and what isolation levels actually change.
  24. networkingHow TLS Actually Secures a ConnectionFrom the ClientHello to the session ticket: what every message in a TLS handshake does, why certificates are the center of the trust model, and how TLS 1.3 changed the game.
  25. databasesWhy Databases Use B-Trees (and Not Hash Tables)Indexes are shaped by the physics of disk and memory. What a B-tree is, why hash indexes can't replace it, and what the shape of the tree says about your database.
  26. operating systemsHow an Operating System Schedules a ThreadBetween your code and the CPU sits a scheduler making decisions every millisecond: priorities, context switches, and the physics of 'the thread was runnable but the OS said no'.
  27. software architectureMonolith First: Why Simple Beats DistributedBefore microservices made sense for anyone, they were a cost center pretending to be scale. A review of when a monolith is the right architecture — and when the call for services is actually a cry for discipline.