A stop-the-world (STW) event is a garbage-collection phase during which application threads are paused. Long pauses can freeze requests and create latency spikes. section 11.4.1
Investigate STW events through GC logs: check pause duration, frequency, and heap recovery. Treat one unusual entry cautiously; recurring long pauses suggest memory pressure or tuning problems. section 11.4.1
Use these questions when reviewing GC output:
- Do pauses repeatedly exceed roughly 50 milliseconds? section 11.4.1
- Are minor or full collections occurring unusually often? section 11.4.1
- Does full GC reclaim little memory, indicating objects may be lingering? section 11.4.1
Reading a pause pattern
A log with pauses rising from 25–27 milliseconds to 110 milliseconds, then 250 milliseconds, 2.567 seconds, and 5.321 seconds shows a recurring deterioration rather than an isolated exception.
