Serviceability in J9
summary
J9 exposes fine-grained knobs (force JIT on/off, set invocation thresholds, limit compilation threads) plus GC and VM options to change one factor at a time, and it records runtime history via per-thread trace buffers that wrap to a fixed size with about 7,000 trace points controllable by level or component. Dump agents produce Java cores, heap dumps or snap snapshots, embedding a core dump structure blob so DDR/JumpView can analyze crashes without symbols and run automated checks (deadlock detection, overlapping shared-memory scan).
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chapters (14)
- 0:00Start
- 11:19Tuning - JIT
- 18:11History - Sources
- 20:10History - JVM tracing
- 23:20History - Collection
- 25:38State - Formats
- 30:50Dump agents
- 33:45History and State
- 34:35Analysis
- 35:12Direct Dump Reader (DDR)
- 37:47Native debuggers
- 38:54DDR Interactive/jdmpview
- 46:41Conclusion
- 47:33Important Disclaimers
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