java - 为什么我的堆主要由无法访问的对象组成？

Question

我刚刚在 YourKit 分析器中查看了我的堆转储，并看到了以下可访问/不可访问的统计信息。

这个我不是很清楚。这是否意味着我几乎所有的堆都包含一些垃圾数据，我需要强烈调整我的 G1.或者这是通常的统计数据？

问题:GC 时间约为应用程序运行时间的 10%。

我对无法访问的对象是可以被垃圾收集的对象的理解是否正确，或者 YourKit 意味着它有什么不同？这是一段 GC 日志(使用 CMS):

2.823: [GC (Metadata GC Threshold) [PSYoungGen: 420257K->52400K(564736K)] 420257K->52488K(1854976K), 0.0607756 secs] [Times: user=0.18 sys=0.01, real=0.06 secs] 
2.884: [Full GC (Metadata GC Threshold) [PSYoungGen: 52400K->0K(564736K)] [ParOldGen: 88K->51480K(903680K)] 52488K->51480K(1468416K), [Metaspace: 20809K->20809K(1067008K)], 0.1990115 secs] [Times: user=0.59 sys=0.01, real=0.20 secs] 
5.760: [GC (Metadata GC Threshold) [PSYoungGen: 287353K->65545K(664576K)] 338833K->117033K(1568256K), 0.0571198 secs] [Times: user=0.13 sys=0.02, real=0.06 secs] 
5.818: [Full GC (Metadata GC Threshold) [PSYoungGen: 65545K->0K(664576K)] [ParOldGen: 51488K->103745K(1605120K)] 117033K->103745K(2269696K), [Metaspace: 34820K->34772K(1079296K)], 0.1841317 secs] [Times: user=0.51 sys=0.02, real=0.18 secs] 
9.099: [GC (Allocation Failure) [PSYoungGen: 598528K->61614K(796672K)] 702273K->165367K(2401792K), 0.0557993 secs] [Times: user=0.23 sys=0.03, real=0.06 secs] 
9.965: [GC (Allocation Failure) [PSYoungGen: 796334K->33251K(969216K)] 900087K->173388K(2574336K), 0.0492724 secs] [Times: user=0.22 sys=0.04, real=0.05 secs] 
11.085: [GC (Allocation Failure) [PSYoungGen: 969187K->49292K(1016320K)] 1109324K->189430K(2621440K), 0.0904503 secs] [Times: user=0.40 sys=0.00, real=0.09 secs] 
11.855: [GC (Allocation Failure) [PSYoungGen: 985228K->64233K(1375232K)] 1125366K->204379K(2980352K), 0.1003579 secs] [Times: user=0.38 sys=0.06, real=0.10 secs] 
12.625: [GC (Allocation Failure) [PSYoungGen: 1363689K->75774K(1375232K)] 1503835K->227247K(2980352K), 0.0790738 secs] [Times: user=0.37 sys=0.16, real=0.08 secs] 
13.341: [GC (Allocation Failure) [PSYoungGen: 1375230K->87028K(2066944K)] 1526703K->249534K(3672064K), 0.1147762 secs] [Times: user=0.55 sys=0.09, real=0.12 secs] 
14.375: [GC (Allocation Failure) [PSYoungGen: 2066932K->98795K(2078720K)] 2229438K->284557K(3683840K), 0.1174134 secs] [Times: user=0.57 sys=0.18, real=0.12 secs] 
15.465: [GC (Allocation Failure) [PSYoungGen: 2078699K->117243K(2798080K)] 2264461K->317809K(4403200K), 0.1130871 secs] [Times: user=0.76 sys=0.19, real=0.11 secs] 
16.769: [GC (Allocation Failure) [PSYoungGen: 2798075K->134647K(2815488K)] 2998641K->363601K(4420608K), 0.1855432 secs] [Times: user=1.05 sys=0.29, real=0.19 secs] 
18.117: [GC (Allocation Failure) [PSYoungGen: 2815479K->133511K(3842560K)] 3044433K->411609K(5447680K), 0.2329040 secs] [Times: user=0.81 sys=0.13, real=0.23 secs] 
19.965: [GC (Allocation Failure) [PSYoungGen: 3816327K->117907K(3852288K)] 4094425K->476525K(5457408K), 0.1902845 secs] [Times: user=1.06 sys=0.33, real=0.19 secs] 
21.745: [GC (Allocation Failure) [PSYoungGen: 3800723K->70957K(4020224K)] 4159341K->541079K(5625344K), 0.1766376 secs] [Times: user=1.02 sys=0.33, real=0.17 secs] 
23.425: [GC (Allocation Failure) [PSYoungGen: 3924781K->73249K(4021760K)] 4394903K->607715K(5626880K), 0.1285575 secs] [Times: user=0.70 sys=0.18, real=0.13 secs] 
25.186: [GC (Allocation Failure) [PSYoungGen: 3927073K->73147K(4021248K)] 4461539K->674821K(5626368K), 0.1243413 secs] [Times: user=0.69 sys=0.21, real=0.12 secs] 
26.906: [GC (Allocation Failure) [PSYoungGen: 3936187K->72831K(4022272K)] 4537861K->741865K(5627392K), 0.1476289 secs] [Times: user=0.85 sys=0.29, real=0.15 secs] 
28.644: [GC (Allocation Failure) [PSYoungGen: 3935871K->74110K(4028928K)] 4604905K->811056K(5634048K), 0.1401820 secs] [Times: user=0.58 sys=0.38, real=0.14 secs] 
30.420: [GC (Allocation Failure) [PSYoungGen: 3954046K->74890K(4030464K)] 4690992K->880140K(5635584K), 0.1217263 secs] [Times: user=1.02 sys=0.14, real=0.12 secs] 
32.119: [GC (Allocation Failure) [PSYoungGen: 3954826K->74036K(4038656K)] 4760076K->947726K(5643776K), 0.1349601 secs] [Times: user=0.79 sys=0.17, real=0.14 secs] 
33.844: [GC (Allocation Failure) [PSYoungGen: 3971892K->74611K(4039680K)] 4845582K->1016221K(5644800K), 0.1579372 secs] [Times: user=1.31 sys=0.18, real=0.16 secs] 
35.604: [GC (Allocation Failure) [PSYoungGen: 3972467K->73896K(4047360K)] 4914077K->1084130K(5652480K), 0.1553432 secs] [Times: user=0.89 sys=0.09, real=0.16 secs] 
37.416: [GC (GCLocker Initiated GC) [PSYoungGen: 3988648K->73759K(4048384K)] 4998892K->1152107K(5653504K), 0.1948397 secs] [Times: user=0.94 sys=0.18, real=0.19 secs] 
39.315: [GC (Allocation Failure) [PSYoungGen: 3988511K->74582K(4056064K)] 5066932K->1221883K(5661184K), 0.1410819 secs] [Times: user=0.83 sys=0.34, real=0.14 secs] 
41.105: [GC (Allocation Failure) [PSYoungGen: 4005206K->76174K(4057088K)] 5152507K->1292051K(5662208K), 0.1966487 secs] [Times: user=0.96 sys=0.23, real=0.19 secs] 
42.866: [GC (Allocation Failure) [PSYoungGen: 4006798K->75063K(4064768K)] 5222675K->1361707K(5669888K), 0.1755286 secs] [Times: user=0.77 sys=0.13, real=0.17 secs] 
44.841: [GC (Allocation Failure) [PSYoungGen: 4020535K->76560K(4064768K)] 5307179K->1432324K(5669888K), 0.1492622 secs] [Times: user=0.93 sys=0.23, real=0.15 secs] 
46.652: [GC (Allocation Failure) [PSYoungGen: 4022032K->76593K(4071936K)] 5377796K->1503428K(5677056K), 0.1457041 secs] [Times: user=0.92 sys=0.07, real=0.15 secs] 
48.803: [GC (Allocation Failure) [PSYoungGen: 4035377K->72513K(4071424K)] 5462212K->1570356K(5676544K), 0.1883641 secs] [Times: user=1.09 sys=0.18, real=0.19 secs] 
48.992: [Full GC (Ergonomics) [PSYoungGen: 72513K->0K(4071424K)] [ParOldGen: 1497843K->1521336K(3507200K)] 1570356K->1521336K(7578624K), [Metaspace: 41385K->41378K(1085440K)], 2.5937473 secs] [Times: user=23.36 sys=0.04, real=2.60 secs] 

Answer 1

您的应用程序创建了许多临时对象。这就是 GC 花费如此多时间的原因。请看文章“过多的垃圾分配” https://www.yourkit.com/docs/java/help/excessive_gc.jsp您将能够找到创建临时对象的地方。