我在一個性能至關重要的服務器端Java應用程序上工作。Java老一代不斷增長 - 需要幫助解釋Java GC輸出
一旦系統啓動,我預計不會創建長壽命的物體 - 只有短壽命的物體才能生存(長達10秒)。因此,我希望調整JVM,以便在系統啓動後舊系統保持不變。
我想我已經成功了,但我不明白爲什麼(見下文)。
這是我們的設置:
-Xmx3000m -Xms3000m -verbose:GC -XX:+ PrintGCTimeStamps -XX:+ PrintGCDetails -XX:+ UseConcMarkSweepGC -XX:SurvivorRatio = 5 -XX:TargetSurvivorRatio = 90 -XX :MaxTenuringThreshold = 31 -XX:+ PrintTenuringDistribution -XX:NewSize = 1250m -XX:MaxNewSize = 1250m
我們使用Oracle的Java 1.6。
我真的很困惑「PrintTenuringDistribution」標誌的輸出。我看到的輸出是這樣的:
893.866: [GC 893.866: [ParNew
Desired survivor size 168512712 bytes, new threshold 16 (max 31)
- age 1: 13251072 bytes, 13251072 total
- age 2: 1135456 bytes, 14386528 total
- age 3: 59104 bytes, 14445632 total
- age 4: 467384 bytes, 14913016 total
- age 5: 68688 bytes, 14981704 total
- age 6: 43336 bytes, 15025040 total
- age 7: 41344 bytes, 15066384 total
- age 8: 6872 bytes, 15073256 total
- age 9: 87568 bytes, 15160824 total
- age 10: 23840 bytes, 15184664 total
- age 11: 99712 bytes, 15284376 total
- age 12: 5224 bytes, 15289600 total
- age 13: 1000 bytes, 15290600 total
- age 14: 59056 bytes, 15349656 total
- age 15: 65225584 bytes, 80575240 total
: 1015468K->95478K(1097152K), 0.0268070 secs] 1387738K->467748K(2889152K), 0.0269910 secs] [Times: user=0.31 sys=0.00, real=0.03 secs]
899.179: [GC 899.180: [ParNew
Desired survivor size 168512712 bytes, new threshold 16 (max 31)
- age 1: 12438336 bytes, 12438336 total
- age 2: 1531984 bytes, 13970320 total
- age 3: 87920 bytes, 14058240 total
- age 4: 58824 bytes, 14117064 total
- age 5: 463368 bytes, 14580432 total
- age 6: 68688 bytes, 14649120 total
- age 7: 43336 bytes, 14692456 total
- age 8: 40136 bytes, 14732592 total
- age 9: 6872 bytes, 14739464 total
- age 10: 87568 bytes, 14827032 total
- age 11: 23840 bytes, 14850872 total
- age 12: 99712 bytes, 14950584 total
- age 13: 2896 bytes, 14953480 total
- age 14: 1000 bytes, 14954480 total
- age 15: 65282456 bytes, 80236936 total
: 1009782K->98799K(1097152K), 0.0383370 secs] 1382052K->471069K(2889152K), 0.0385490 secs] [Times: user=0.36 sys=0.00, real=0.03 secs]
既然我有很多與年齡= 15個對象中,閾值是16,我希望在一個GC或者(a)被提升到老的每個對象一代,或(b)垃圾收集。
但根據JConsole,我的老一代並沒有增加。那麼所有這些物體發生了什麼?
你應該做一個堆轉儲並將其發送到客戶端進行分析:) –
從日誌看,它看起來像最大的年齡是31 – rohitmohta