We are using parallel gc with 1.7.0_71.
java -XX:+PrintCommandLineFlags -XX:+PrintGCDetails -version
-XX:InitialHeapSize=258222272 -XX:MaxHeapSize=4131556352 -XX:+PrintCommandLineFlags -XX:+PrintGCDetails -XX:+UseCompressedOops -XX:+UseParallelGC
java version "1.7.0_71"
Java(TM) SE Runtime Environment (build 1.7.0_71-b14)
Java HotSpot(TM) 64-Bit Server VM (build 24.71-b01, mixed mode)
We see huge garbage created in our application every few minutes at a decent load. Minor gc fires every few seconds and main gc triggers every 2 minutes. In our analysis, we found that 1.8 million char array objects each of 173K sizes remained on the heap. Minor gc cannot restore them. When extracting heapdump, we found many objects in the remainder section in Ecclpe's Mcl. The MAT histogram shows a lot of char arrays (they are displayed in html), however, all incoming links and merge paths to the gc root are not available for the char array, but only a full GC can restore only non-GC ones. Why can't a secondary GC restore them if there are no object references? Photos of the Eclipse MAT are attached. See All Links Unavailable.
There was some reference to the request objects, cleared them by setting zeros.
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https://www.dropbox.com/sh/qgsitzb7x27j8kc/AABoQwR1qPwTPiDtO6B0_Pm7a?dl=0
, ? JBoss 7.1.1 wildfly 8.2.0.Final. gc JDK. gc , .
XX: NewRatio 1. , , gc
, G1 GC ? ? G1 GC. -Xms: 1024m, -Xmx 2048m. 512
, . gc
2015-05-10 19:32:41 IST| 459.939: [Full GC [PSYoungGen: 8123K->0K(680960K)] [ParOldGen: 782136K->359065K(766464K)] 790260K->359065K(1447424K) [PSPermGen: 202932K->202930K(441344K)], 1.0738240 secs] [Times: user=3.37 sys=0.01, real=1.07 secs]
2015-05-10 19:32:42 IST| 462.306: [GC [PSYoungGen: 672768K->10534K(685056K)] 1031833K->369600K(1451520K), 0.0450800 secs] [Times: user=0.15 sys=0.00, real=0.04 secs]
2015-05-10 19:32:44 IST| 463.641: [GC [PSYoungGen: 682790K->9093K(685568K)] 1041856K->373085K(1452032K), 0.0570820 secs] [Times: user=0.16 sys=0.00, real=0.06 secs]
2015-05-10 19:32:45 IST| 464.936: [GC [PSYoungGen: 681349K->9812K(686080K)] 1045341K->377511K(1452544K), 0.0439060 secs] [Times: user=0.12 sys=0.00, real=0.04 secs]
2015-05-10 19:32:46 IST| 466.283: [GC [PSYoungGen: 683092K->10733K(686080K)] 1050791K->383554K(1452544K), 0.0464700 secs] [Times: user=0.14 sys=0.00, real=0.05 secs]
2015-05-10 19:32:48 IST| 467.659: [GC [PSYoungGen: 684013K->11283K(685568K)] 1056834K->388651K(1452032K), 0.1381130 secs] [Times: user=0.30 sys=0.00, real=0.14 secs]
2015-05-10 19:32:50 IST| 469.734: [GC [PSYoungGen: 684051K->9652K(686080K)] 1061419K->393759K(1452544K), 0.0466800 secs] [Times: user=0.13 sys=0.00, real=0.05 secs]
2015-05-10 19:32:51 IST| 471.087: [GC [PSYoungGen: 682420K->11253K(685568K)] 1066527K->400087K(1452032K), 0.0589180 secs] [Times: user=0.11 sys=0.00, real=0.06 secs]
2015-05-10 19:32:52 IST| 472.325: [GC [PSYoungGen: 684021K->7957K(686080K)] 1072855K->403018K(1452544K), 0.0436140 secs] [Times: user=0.13 sys=0.00, real=0.04 secs]
2015-05-10 19:32:54 IST| 473.606: [GC [PSYoungGen: 680725K->9177K(685056K)] 1075786K->406493K(1451520K), 0.0524990 secs] [Times: user=0.13 sys=0.00, real=0.05 secs]
2015-05-10 19:34:34 IST| 573.526: [GC [PSYoungGen: 684217K->10956K(686080K)] 1440629K->771626K(1452544K), 0.0416620 secs] [Times: user=0.14 sys=0.00, real=0.04 secs]
2015-05-10 19:34:34 IST| 573.568: [Full GC [PSYoungGen: 10956K->0K(686080K)] [ParOldGen: 760670K->364958K(818688K)] 771626K->364958K(1504768K) [PSPermGen: 203069K->203069K(420864K)], 0.8001740 secs] >[Times: user=2.46 sys=0.01, real=0.80 secs]
2015-05-10 19:34:36 IST| 575.600: [GC [PSYoungGen: 674304K->10465K(686592K)] 1039262K->375423K(1505280K), 0.0410330 secs] [Times: user=0.13 sys=0.00, real=0.04 secs]
2015-05-10 19:36:35 IST| 694.277: [GC [PSYoungGen: 684413K->9342K(687104K)] 1490469K->820033K(1505792K), 0.2160320 secs] [Times: user=0.55 sys=0.08, real=0.21 secs]
2015-05-10 19:36:36 IST| 695.664: [GC [PSYoungGen: 684670K->8323K(687104K)] 1495361K->823380K(1505792K), 0.0454050 secs] [Times: user=0.11 sys=0.00, real=0.05 secs]
2015-05-10 19:36:37 IST| 695.710: [Full GC [PSYoungGen: 8323K->0K(687104K)] [ParOldGen: 815056K->363295K(838144K)] 823380K->363295K(1525248K) [PSPermGen: 203095K->203095K(401920K)], 0.8133080 secs] [Times: user=2.43 sys=0.01, real=0.81 secs]
2015-05-10 19:36:38 IST| 697.669: [GC [PSYoungGen: 675328K->10586K(686592K)] 1038623K->373882K(1524736K), 0.0436000 secs] [Times: user=0.13 sys=0.00, real=0.04 secs]
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