# Ou David — Systems Engineer

I build backend services and platform infrastructure for systems that need to keep working when integrations or data flows get messy. I write about Go, HTTP, protocol design, and the production bugs that make implicit assumptions visible.

## Start with a technical topic

- [Go performance and benchmarks](/tags/benchmarking/): string construction, allocation costs, and runnable case studies.
- [HTTP and backend engineering in Go](/tags/golang/): follow a request from the network to a handler, then look at the code behind it.
- [JSON-RPC and MCP](/tags/json-rpc/): understand the messages first, then build a small Go server.
- [Integration debugging](/topics/integration-debugging/): timezone boundaries, fractional cents, and the assumptions between systems.

## Selected project

[Go Language Case Studies](/projects/go-lang-case-study/) contains the runnable examples, tests, and benchmarks behind my articles. Start with [string concatenation vs. strings.Builder](/posts/go_string_concat_vs_string_builder/) or the [UNIX process API example](/posts/process_api_behind_every_shell_command/).

[More about my backend and platform work](/about/) · [All projects](/projects/)

## Explore

- [Home](https://vvivid.dev/)
- [Blog](https://vvivid.dev/posts/)
- [About Me](https://vvivid.dev/about/)
- [Projects](https://vvivid.dev/projects/)

## Recent posts

- [What Really Happens When You Run a Shell Command?](https://vvivid.dev/posts/process_api_behind_every_shell_command/) · [Markdown](https://vvivid.dev/posts/process_api_behind_every_shell_command/index.md) · 2026-06-15
  How three UNIX process primitives make execution, redirection, and pipelines possible.
- [String Concatenation vs strings.Builder in Go](https://vvivid.dev/posts/go_string_concat_vs_string_builder/) · [Markdown](https://vvivid.dev/posts/go_string_concat_vs_string_builder/index.md) · 2026-06-13
  A small Go benchmark showing when repeated string concatenation becomes expensive and how strings.Builder changes the allocation profile.
- [The Trap of Vibe Coding for Juniors](https://vvivid.dev/posts/the_trap_of_vibe_coding_for_juniors/) · [Markdown](https://vvivid.dev/posts/the_trap_of_vibe_coding_for_juniors/index.md) · 2026-01-27
  Why AI-generated code becomes risky when juniors cannot judge the design, failure modes, or maintenance cost.
- [Handling Fractional Cents in Integrations](https://vvivid.dev/posts/handling_fractional_cents_integration/) · [Markdown](https://vvivid.dev/posts/handling_fractional_cents_integration/index.md) · 2026-01-21
  How a design flaw in POS integration led to a 0.01 Euro discrepancy and how we solved it.
- [The Silent Timezone Mismatch: Go vs MongoDB](https://vvivid.dev/posts/the_silent_timezone_mismatch_go_vs_mongodb/) · [Markdown](https://vvivid.dev/posts/the_silent_timezone_mismatch_go_vs_mongodb/index.md) · 2026-01-16
  How implicit conversions between primitive.DateTime and time.Time can cause subtle bugs.


[All posts](https://vvivid.dev/posts/) · [Markdown listing](https://vvivid.dev/posts/index.md)

## Reading this site

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