Java GC日誌行之間有什麼區別？ （「總共歷時......」 VS「[GC」）

Question

Java版本： 1.6.0_20

我看到在我的日誌下面，我試圖找出差異在第一行和後面的行之間。據我所知，它們都與GC有關，但是它們之間並沒有一對一的關係，正如我讀過的其他GC教程中通常所說的那樣。我知道如何解釋第一行，第二行也很明顯，但這兩個事件之間的區別是什麼？

30171.470: [GC 30171.470: [ParNew: 32704K->64K(32704K), 0.0055740 secs] 1575471K->1545444K(3145664K), 0.0056610 secs] [Times: user=0.04 sys=0.00, real=0.01 secs] 
Total time for which application threads were stopped: 0.0060020 seconds 
Total time for which application threads were stopped: 0.0003300 seconds 
Total time for which application threads were stopped: 0.0000740 seconds 
Total time for which application threads were stopped: 0.0002630 seconds 
Total time for which application threads were stopped: 0.0002640 seconds 
Total time for which application threads were stopped: 0.0000760 seconds 
... Snipped 35 similar lines ... 
Total time for which application threads were stopped: 0.0006710 seconds 
Total time for which application threads were stopped: 0.0000870 seconds 
Total time for which application threads were stopped: 0.0002710 seconds 
Total time for which application threads were stopped: 0.0000770 seconds 
Total time for which application threads were stopped: 0.0002810 seconds 
Total time for which application threads were stopped: 0.0002680 seconds 
Total time for which application threads were stopped: 0.0000770 seconds 
30289.137: [GC 30289.137: [ParNew: 32704K->63K(32704K), 0.0063990 secs] 1578084K->1548229K(3145664K), 0.0064890 secs] [Times: user=0.04 sys=0.00, real=0.01 secs] 

感謝您的幫助！

Answer 1

「......應用程序線程」消息由PrintGCApplicationStoppedTime控制。只要JVM到達safepoint操作的結尾，它就會檢查是否應該打印該操作期間應用程序停止的時間。

國旗的名稱有些誤導性，因爲它與GC沒有特別的關係。例如，如果您也使用PrintSafepointStatistics標誌運行，則您可能會看到大多數VM操作是RevokeBias。與GC相關的操作將命名爲GenCollectForAllocation。