TimeoutException ☕ Java

java.util.concurrent.TimeoutException

A Future.get(timeout) or async operation didn’t complete in the allowed time.

Seen on: Java

Meaning

The task is still running (or stuck) when the timeout elapses. Slow downstream calls, deadlocks or thread-pool starvation are typical.

Common causes

  • Slow downstream service
  • Thread pool too small / all threads blocked
  • Deadlock
  • Timeout set too low

⚡ Quick fix

  1. Measure the task’s real duration
  2. Increase pool size or use separate pools for blocking work
  3. Add timeouts to downstream calls themselves

Detailed fix by platform

Java

  1. Take a thread dump (jstack <pid>) while it hangs to see what threads are waiting on

How to diagnose

  1. Task — What is it waiting for?
  2. Pool — Threads available?

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