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This article explains the internal mechanisms of JVM garbage collection, covering oopMap, safepoints, saferegions, three‑color marking, memory sets, write barriers, and the design of low‑latency collectors such as Shenandoah and ZGC, and provides practical tuning advice.
JVM safepoints are pause points where the VM can stop all threads for operations like garbage collection; the article shows how counted loops can prevent threads from reaching safepoints, causing unexpected long sleeps, and explains tuning flags, loop‑counter changes, and best practices to avoid STW pauses.
This article examines the puzzling 'prevent gc' comment and Thread.sleep(0) call in RocketMQ’s source, explains how it leverages JVM safepoint mechanics to trigger garbage collection, discusses counted vs uncounted loops, and demonstrates practical code modifications to improve performance.
This article details a systematic investigation of various backend performance problems—including CMS GC delays, biased‑lock revocation, Netty worker thread blocking, and log‑framework overhead—provides root‑cause analysis, JVM tuning parameters, and practical recommendations to mitigate latency spikes in production services.
After weeks of investigation, this post details how intermittent request timeouts in a high‑concurrency Java service were traced to frequent JVM stop‑the‑world pauses caused by GC, safepoint logging, biased lock revocation, and Log4j2’s synchronous logging, and outlines the steps taken to diagnose and resolve the issue.