ReferenceGlossary
Thread pool
A fixed set of threads that take work from a shared queue, so a program does not pay to create a thread per task. In a thread-per-request server, the pool size limits how many requests run at once, and a request that waits on I/O still holds its thread.
Runtimes
In Quorum#
Java's Tomcat runs 200 threads in one JVM, and Ruby's Puma runs 5 threads per process: each waiting request holds a thread, so slow database calls can fill the pool. For Node.js, the libuv thread pool Research moves password hashing off the event loop, so logins stop stalling other requests. Rust's Tokio runs async tasks on a pool of worker threads, where a CPU-heavy task blocks only one of them.