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Java Day Tokyo 2013 Java The Night - G1GCVisualizer -
- 1. G1GCを可視化してみました - G1GC Visualizer - 徳益芳郎 (某メーカー勤務) Java Day Tokyo 2013 Java The Night
- 4. へぇー
- 5. G1GC の各世代管理 各世代は Region の集 合で表現 各世代の Region は必 要なときに必要なだけ 確保 Permanent 領域は Region 単位の管理外 Old Humongous Survivor Eden Eden Eden EdenEden Survivor Permanent Old Old Old Old Old Old Old OldOld Old Old Old Old OldOld Old Old Old Old
- 6. 退避 GC Old Humongous Permanent Old Old Old Old Old Old Old OldOld Old Old OldOld Old Old Old Old Eden Eden EdenEden Survivor Old Old Collection Set 内の Lived オブジェクトを他の Region に退避する Eden Old Humongous Permanent Old Old Old Old Old Old OldOld Old Old OldOld Old Old Old Old Survivor Old Old Old Evacuate Eden Eden EdenEden Survivor Eden
- 9. でも、期待と違った！ Old Humongous Survivor Eden Eden Eden EdenEden SurvivorOld Old Old Old Old Old Old OldOld Old Old Old Old OldOld Old Old Old Old ?Region管理を イメージできない！
- 10. .... 311.040: [GC pause (young) (initial-mark), 0.00690255 secs] [Parallel Time: 6.6 ms] [GC Worker Start (ms): 311039.8 311039.8 311039.9 311045.7 Avg: 311041.3, Min: 311039.8, Max: 311045.7, Diff: 5.8] [Ext Root Scanning (ms): 3.0 4.0 5.0 0.0 Avg: 3.0, Min: 0.0, Max: 5.0, Diff: 5.0] [Update RS (ms): 1.6 0.7 0.1 0.0 Avg: 0.6, Min: 0.0, Max: 1.6, Diff: 1.6] ... Avg: 0.1, Min: 0.0, Max: 0.1, Diff: 0.1] [Termination Attempts : 1 1 1 1 Sum: 4, Avg: 1, Min: 1, Max: 1, Diff: 0] [GC Worker End (ms): 311045.7 311045.7 311045.7 311045.7 Avg: 311045.7, Min: 311045.7, Max: 311045.7, Diff: 0.0] [GC Worker (ms): 5.9 5.9 5.8 0.0 Avg: 4.4, Min: 0.0, Max: 5.9, Diff: 5.9] [GC Worker Other (ms): 0.8 0.8 0.8 6.6 Avg: 2.2, Min: 0.8, Max: 6.6, Diff: 5.9] [Clear CT: 0.0 ms] .... GCログを出力してみた -XX:+UseG1GC -Xloggc:<file> -XX:+PrintGCDetails -XX:+UnlockDiagnosticVMOptions -XX:+G1PrintHeapRegions .... G1HR ALLOC(Eden) 0x04c00000 G1HR ALLOC(Eden) 0x04000000 G1HR ALLOC(Eden) 0x05c00000 G1HR ALLOC(Eden) 0x04600000 G1HR ALLOC(Eden) 0x05d00000 G1HR #StartGC 261 G1HR CSET 0x04600000 G1HR CSET 0x05c00000 G1HR CSET 0x04000000 G1HR CSET 0x04c00000 G1HR CSET 0x04900000 G1HR REUSE 0x05500000 G1HR ALLOC(Survivor) 0x04b00000 G1HR RETIRE 0x04b00000 0x04b313d0 G1HR RETIRE 0x05500000 0x0553aa60 G1HR #EndGC 261 .... Old Humongous Survivor Eden Eden Eden EdenEden SurvivorOld Old Old Old Old Old Old OldOld Old Old Old Old OldOld Old Old Old Old ?やっぱり、Region管理を イメージできない！
- 12. で、作ってみた... .... G1HR ALLOC(Eden) 0x04c00000 G1HR ALLOC(Eden) 0x04000000 G1HR ALLOC(Eden) 0x05c00000 G1HR ALLOC(Eden) 0x04600000 G1HR ALLOC(Eden) 0x05d00000 G1HR #StartGC 261 G1HR CSET 0x04600000 G1HR CSET 0x05c00000 G1HR CSET 0x04000000 G1HR CSET 0x04c00000 G1HR CSET 0x04900000 G1HR REUSE 0x05500000 G1HR ALLOC(Survivor) 0x04b00000 G1HR RETIRE 0x04b00000 0x04b313d0 G1HR RETIRE 0x05500000 0x0553aa60 G1HR #EndGC 261 ....
- 13. なんとなくイメージできた！？
- 14. Region の状態を可視化
- 16. G1GC イベントも可視化 COMMIT / UNCOMMIT ヒープ領域の拡張・縮退 ALLOC / ALLOC-FORCE 各世代への Region 割当 CSET 退避する Region の選定 RETIRE Region の満杯前に退避終了 REUSE 退避先として既存 Regionを再利用 CLEAN CMS による Region の開放 POST-COMPACTION Full GC による Region 開放 EVAC-FAILRE Region 退避の失敗
- 17. Demo
- 18. 終わり