5 posts
Comparing how the Micrometer (library) approach and the OTel Java Agent (bytecode manipulation) approach work — a look inside premain, the Instrumentation API, and ByteBuddy code injection.
How to propagate context in coroutines, where the thread can change at every suspend point — the structure of CoroutineContext, ThreadContextElement, and bridging ThreadLocal with asContextElement().
Why ThreadLocal-based traceId propagation fails on the WebFlux event loop, and how Reactor Context's bottom-up propagation model solves it — with hands-on examples.
How ThreadLocal works under the hood, how MDC gets traceId into your logs, and the moments Spring MVC actually switches threads — the fundamentals you need before going async.
Why the three pillars of observability need distributed tracing, the history from Zipkin B3 through the OpenTracing/OpenCensus split to the OpenTelemetry merger, and where the Spring ecosystem stands today.