ClassLoader leaks are among the most hidden and difficult-to-diagnose runtime problems in long-lived JVM systems, and a common challenge faced by long-running JVM workloads across the Apache ecosystem. Existing approaches largely remain at the "post-mortem investigation" stage: monitoring tools and heap dumps can tell developers "which ClassLoaders are still alive," but struggle to clearly explain "why they cannot be reclaimed," let alone translate governance intent into verifiable, reproducible engineering practices.

Through deep analysis of Apache SeaTunnel's classloading mechanism, we identified a widely overlooked blind spot: a large number of seemingly correct lifecycle implementations never establish explicit resource-close semantics. Without enforced close and drain constraints, resource reclamation becomes highly unpredictable — and in certain scenarios, leads to ClassLoaders that can never be collected.

Drawing on our exploration of runtime governance for long-lived JVM systems, we proposed a systematic ClassLoader lifecycle governance improvement plan to the Apache SeaTunnel community. The core shift is from passive "post-hoc residual reference hunting" to proactive "building deterministic reclaimable semantics and lifecycle closure." We incrementally introduced explicit lifecycle close mechanisms, enforced classloading boundary constraints, and active residual reference cleanup. The governance proposal is currently under community discussion, with the Phase 1 optimization PR in review.

This talk will explore real-world community practices in Apache SeaTunnel, covering:

1. Why long-lived systems cannot rely on implicit GC to manage underlying runtime resources
2. How to build a ClassLoader governance standard for long-lived JVM systems and progressively land it in Apache open source projects
3. How to complete a smooth, kernel-level architectural governance upgrade without breaking compatibility