JVM Options

• -Xms256m
• -Xmx512m
• -Xss256k
• -XX:PermSize=128m
• -XX:MaxPermSize=128M
• -XX:SurvivorRatio=7
• -XX:NewRatio=2
• -XX:MaxTenuringThreshold=8

Explain

• Young Gen: 170.626, 85.356
  • Eden Space: 132.750, 66.438
  • Survivor: 37.876, 18.876
    • Survivor 0: 18.938, 9.438
    • Survivor 1: 18.938, 9.438
• Old Gen: 341.375, 170.688
• Perm Gen: 128, 128
• -Xms: 85.356 + 170.688 = 256.044
• -Xmx: 170.626 + 341.375 = 512.001
• -XX:SurvivorRatio=7
  • Eden: Survivor = 7: 2
  • Eden: 170.626 * 7/9 = 132.22, 85.356 * 7/9 = 66.388
  • Survivor: 170.626 * 2/9 = 37.917, 85.356 * 2/9 = 18.968
• -XX:NewRatio=2
  • Young Gen: Old Gen= 1: 2
  • 170.626: 341.375= 1:2
  • 85.356: 170.688= 1:2

Reference

• JVM Settings
• Java Options
• JDK Tools and Utilities
• Java HotSpot VM Options
• JVM调优总结
• GC大揭秘