Learning paths · Skills · Intermediate

Spring Boot: how a request becomes a response

What Spring Boot does between an HTTP request arriving and a response leaving: the container that builds your objects, the proxies that wrap them, the threads, transactions and connections each request borrows, and how to see and test it all.

0 of 12 done

The map

Not started
In progress
Done
Builds on

01The containerBeans, wiring and auto-configuration

02A request's journeyThreads, filters, proxies, transactions

03Data and productionQueries, pools, signals and tests

04Next: system designSame ideas, at service scale

BulkheadLibrary ↗Tomcat's thread pool and Hikari's connection pool are bulkheads already. Give each downstream dependency its own, so one slow service can't take every thread.

TimeoutLibrary ↗A request holds a thread and often a connection until it ends. Timeouts on every outgoing call are what give them back.

Circuit breakerLibrary ↗When a dependency keeps failing, stop calling it for a while; in Spring this is usually Resilience4j, applied through the same kind of proxy as @Transactional.

Cache-asideLibrary ↗@Cacheable is cache-aside behind a proxy: look in the cache, otherwise load and store. The self-invocation trap applies here too.

01The containerBeans, wiring and auto-configuration0/4
02A request's journeyThreads, filters, proxies, transactions0/4
03Data and productionQueries, pools, signals and tests0/4
04Next: system designSame ideas, at service scale

Written for Spring Boot 3.x on Spring Framework 6.x and Java 17 or later; the links point to the 3.5 and 6.2 reference docs.

Where this path leads