Jvm G1 GC何时会触发IHOP之外的初始标记_Jvm_G1gc

Jvm G1 GC何时会触发IHOP之外的初始标记

jvm

Jvm G1 GC何时会触发IHOP之外的初始标记,jvm,g1gc,Jvm,G1gc,我在JDK8中设置了-XX:InitiatingHeapOccupencyPercent=70（没有自适应IHOP特性），但是我发现当HeapOccupancPercent远远小于70%时，JVM启动的开始有两个初始标记阶段，是否还有其他因素会触发G1 GC初始标记阶段？提前谢谢 GC日志摘录： 2020-01-22T03:58:14.227+0000:3.158:[GC暂停（元数据GC阈值）（年轻）（初始标记），0.1583711秒] [伊甸园：1056.0M（81920.0M）->0.0B（

我在JDK8中设置了-XX:InitiatingHeapOccupencyPercent=70（没有自适应IHOP特性），但是我发现当HeapOccupancPercent远远小于70%时，JVM启动的开始有两个初始标记阶段，是否还有其他因素会触发G1 GC初始标记阶段？提前谢谢

GC日志摘录：

2020-01-22T03:58:14.227+0000:3.158:[GC暂停（元数据GC阈值）（年轻）（初始标记），0.1583711秒] [伊甸园：1056.0M（81920.0M）->0.0B（81184.0M）幸存者：0.0B->736.0M堆：1472.0M（160.0G）->1179.5M（160.0G）]

2020-01-22T04:13:07.073+0000:896.004:[GC暂停（G1疏散暂停）（年轻）（初始标记），3.8512514秒] [伊甸园：81184.0M（81184.0M）->0.0B（71904.0M）幸存者：736.0M->10016.0M堆：83643.5M（160.0G）->11744.0M（160.0G）]

JDK版本：

openjdk版本“1.8.0_222”

OpenJDK运行时环境（build 1.8.0_222-b10）

OpenJDK 64位服务器虚拟机（构建25.222-b10，混合模式）

谢谢

******更新2020/02/01 GC日志************

2020-01-22T03:58:14.227+0000:3.158:[GC暂停（元数据GC阈值）（年轻）（初始标记），0.1583711秒]

[平行时间：143.8 ms，GC工作人员：33]

 [GC Worker Start (ms): Min: 3158.7, Avg: 3159.4, Max: 3159.8, Diff: 1.1]

 [Ext Root Scanning (ms): Min: 0.6, Avg: 1.1, Max: 2.7, Diff: 2.1, Sum: 35.9]

 [Update RS (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.1]

    [Processed Buffers: Min: 0, Avg: 0.1, Max: 2, Diff: 2, Sum: 4]

 [Scan RS (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.2]

 [Code Root Scanning (ms): Min: 0.0, Avg: 0.3, Max: 5.9, Diff: 5.9, Sum: 8.5]

 [Object Copy (ms): Min: 135.7, Avg: 141.1, Max: 141.5, Diff: 5.9, Sum: 4654.7]

 [Termination (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.7]

    [Termination Attempts: Min: 1, Avg: 9.1, Max: 15, Diff: 14, Sum: 301]

 [GC Worker Other (ms): Min: 0.0, Avg: 0.0, Max: 0.1, Diff: 0.1, Sum: 0.9]

 [GC Worker Total (ms): Min: 142.0, Avg: 142.5, Max: 143.1, Diff: 1.1, Sum: 4701.0]

 [GC Worker End (ms): Min: 3301.8, Avg: 3301.9, Max: 3301.9, Diff: 0.1]

 [Queue Fixup (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]

 [Table Fixup (ms): Min: 0.0, Avg: 0.0, Max: 0.7, Diff: 0.7, Sum: 0.7]

 [GC Worker Start (ms): Min: 896005.5, Avg: 896006.2, Max: 896006.6, Diff: 1.1]

 [Ext Root Scanning (ms): Min: 4.3, Avg: 5.3, Max: 8.4, Diff: 4.1, Sum: 175.2]

 [Update RS (ms): Min: 0.0, Avg: 0.2, Max: 0.8, Diff: 0.8, Sum: 7.6]

    [Processed Buffers: Min: 0, Avg: 1.3, Max: 6, Diff: 6, Sum: 44]

 [Scan RS (ms): Min: 2254.9, Avg: 2266.4, Max: 2268.2, Diff: 13.3, Sum: 74790.0]

 [Code Root Scanning (ms): Min: 0.0, Avg: 0.7, Max: 10.4, Diff: 10.4, Sum: 23.8]

 [Object Copy (ms): Min: 1535.2, Avg: 1537.7, Max: 1548.1, Diff: 13.0, Sum: 50745.7]

 [Termination (ms): Min: 0.0, Avg: 11.2, Max: 13.3, Diff: 13.2, Sum: 368.0]

    [Termination Attempts: Min: 1, Avg: 2270.1, Max: 2464, Diff: 2463, Sum: 74914]

 [GC Worker Other (ms): Min: 0.0, Avg: 0.2, Max: 0.5, Diff: 0.5, Sum: 8.1]

 [GC Worker Total (ms): Min: 3821.2, Avg: 3821.8, Max: 3822.5, Diff: 1.3, Sum: 126118.4]

 [GC Worker End (ms): Min: 899827.7, Avg: 899827.9, Max: 899828.2, Diff: 0.5]

 [Queue Fixup (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]

 [Table Fixup (ms): Min: 0.0, Avg: 0.1, Max: 1.0, Diff: 1.0, Sum: 1.9]

[代码根修复：0.1毫秒]

[代码根清除：0.0毫秒]

[字符串重复数据消除修复：0.9毫秒，GC工作人员：33]

 [GC Worker Start (ms): Min: 3158.7, Avg: 3159.4, Max: 3159.8, Diff: 1.1]

 [Ext Root Scanning (ms): Min: 0.6, Avg: 1.1, Max: 2.7, Diff: 2.1, Sum: 35.9]

 [Update RS (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.1]

    [Processed Buffers: Min: 0, Avg: 0.1, Max: 2, Diff: 2, Sum: 4]

 [Scan RS (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.2]

 [Code Root Scanning (ms): Min: 0.0, Avg: 0.3, Max: 5.9, Diff: 5.9, Sum: 8.5]

 [Object Copy (ms): Min: 135.7, Avg: 141.1, Max: 141.5, Diff: 5.9, Sum: 4654.7]

 [Termination (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.7]

    [Termination Attempts: Min: 1, Avg: 9.1, Max: 15, Diff: 14, Sum: 301]

 [GC Worker Other (ms): Min: 0.0, Avg: 0.0, Max: 0.1, Diff: 0.1, Sum: 0.9]

 [GC Worker Total (ms): Min: 142.0, Avg: 142.5, Max: 143.1, Diff: 1.1, Sum: 4701.0]

 [GC Worker End (ms): Min: 3301.8, Avg: 3301.9, Max: 3301.9, Diff: 0.1]

 [Queue Fixup (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]

 [Table Fixup (ms): Min: 0.0, Avg: 0.0, Max: 0.7, Diff: 0.7, Sum: 0.7]

 [GC Worker Start (ms): Min: 896005.5, Avg: 896006.2, Max: 896006.6, Diff: 1.1]

 [Ext Root Scanning (ms): Min: 4.3, Avg: 5.3, Max: 8.4, Diff: 4.1, Sum: 175.2]

 [Update RS (ms): Min: 0.0, Avg: 0.2, Max: 0.8, Diff: 0.8, Sum: 7.6]

    [Processed Buffers: Min: 0, Avg: 1.3, Max: 6, Diff: 6, Sum: 44]

 [Scan RS (ms): Min: 2254.9, Avg: 2266.4, Max: 2268.2, Diff: 13.3, Sum: 74790.0]

 [Code Root Scanning (ms): Min: 0.0, Avg: 0.7, Max: 10.4, Diff: 10.4, Sum: 23.8]

 [Object Copy (ms): Min: 1535.2, Avg: 1537.7, Max: 1548.1, Diff: 13.0, Sum: 50745.7]

 [Termination (ms): Min: 0.0, Avg: 11.2, Max: 13.3, Diff: 13.2, Sum: 368.0]

    [Termination Attempts: Min: 1, Avg: 2270.1, Max: 2464, Diff: 2463, Sum: 74914]

 [GC Worker Other (ms): Min: 0.0, Avg: 0.2, Max: 0.5, Diff: 0.5, Sum: 8.1]

 [GC Worker Total (ms): Min: 3821.2, Avg: 3821.8, Max: 3822.5, Diff: 1.3, Sum: 126118.4]

 [GC Worker End (ms): Min: 899827.7, Avg: 899827.9, Max: 899828.2, Diff: 0.5]

 [Queue Fixup (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]

 [Table Fixup (ms): Min: 0.0, Avg: 0.1, Max: 1.0, Diff: 1.0, Sum: 1.9]

[清晰CT:0.4毫秒]

[其他：13.1毫秒]

 [Choose CSet: 0.0 ms]

 [Ref Proc: 9.4 ms]

 [Ref Enq: 0.9 ms]

 [Redirty Cards: 0.6 ms]

 [Humongous Register: 0.2 ms]

 [Humongous Reclaim: 0.0 ms]

 [Free CSet: 0.1 ms]

[伊甸园：1056.0M（81920.0M）->0.0B（81184.0M）幸存者：0.0B->736.0M堆：1472.0M（160.0G）->1179.5M（160.0G）]

[次数：user=1.77 sys=2.98，real=0.15秒]

2020-01-22T03:58:14.386+0000:3.316:[GC并发根区域扫描开始]

2020-01-22T03:58:14.458+0000:3.388:[GC并发标记开始]

2020-01-22T03:58:14.458+0000:3.388:[GC并发根区域扫描结束，0.0718879秒]

2020-01-22T03:58:14.485+0000:3.416:[GC备注2020-01-22T03:58:14.485+0000:3.416:[Finalize Marking，0.0011542 secs]2020-01-22T03:58:14.486+0000:3.417:[GC ref proc，0.0072547 secs]2020-01-22T03:58:14.494+0000:3.424:[卸货，0.0050159 secs]，0.0151448 secs]

[次数：用户=0.19系统=0.02，实际=0.02秒]

2020-01-22T03:58:14.485+0000:3.415:[GC并发标记结束，0.0271495秒]

2020-01-22T03:58:14.500+0000:3.431:[GC清理1259M->1259M（160G），0.0033890秒]

[次数：用户=0.06系统=0.00，实际=0.00秒]

2020-01-22T04:13:07.073+0000:896.004:[GC暂停（G1疏散暂停）（年轻）（初始标记），3.8512514秒]

[并行时间：3822.9 ms，GC工作人员：33]

 [GC Worker Start (ms): Min: 3158.7, Avg: 3159.4, Max: 3159.8, Diff: 1.1]

 [Ext Root Scanning (ms): Min: 0.6, Avg: 1.1, Max: 2.7, Diff: 2.1, Sum: 35.9]

 [Update RS (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.1]

    [Processed Buffers: Min: 0, Avg: 0.1, Max: 2, Diff: 2, Sum: 4]

 [Scan RS (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.2]

 [Code Root Scanning (ms): Min: 0.0, Avg: 0.3, Max: 5.9, Diff: 5.9, Sum: 8.5]

 [Object Copy (ms): Min: 135.7, Avg: 141.1, Max: 141.5, Diff: 5.9, Sum: 4654.7]

 [Termination (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.7]

    [Termination Attempts: Min: 1, Avg: 9.1, Max: 15, Diff: 14, Sum: 301]

 [GC Worker Other (ms): Min: 0.0, Avg: 0.0, Max: 0.1, Diff: 0.1, Sum: 0.9]

 [GC Worker Total (ms): Min: 142.0, Avg: 142.5, Max: 143.1, Diff: 1.1, Sum: 4701.0]

 [GC Worker End (ms): Min: 3301.8, Avg: 3301.9, Max: 3301.9, Diff: 0.1]

 [Queue Fixup (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]

 [Table Fixup (ms): Min: 0.0, Avg: 0.0, Max: 0.7, Diff: 0.7, Sum: 0.7]

 [GC Worker Start (ms): Min: 896005.5, Avg: 896006.2, Max: 896006.6, Diff: 1.1]

 [Ext Root Scanning (ms): Min: 4.3, Avg: 5.3, Max: 8.4, Diff: 4.1, Sum: 175.2]

 [Update RS (ms): Min: 0.0, Avg: 0.2, Max: 0.8, Diff: 0.8, Sum: 7.6]

    [Processed Buffers: Min: 0, Avg: 1.3, Max: 6, Diff: 6, Sum: 44]

 [Scan RS (ms): Min: 2254.9, Avg: 2266.4, Max: 2268.2, Diff: 13.3, Sum: 74790.0]

 [Code Root Scanning (ms): Min: 0.0, Avg: 0.7, Max: 10.4, Diff: 10.4, Sum: 23.8]

 [Object Copy (ms): Min: 1535.2, Avg: 1537.7, Max: 1548.1, Diff: 13.0, Sum: 50745.7]

 [Termination (ms): Min: 0.0, Avg: 11.2, Max: 13.3, Diff: 13.2, Sum: 368.0]

    [Termination Attempts: Min: 1, Avg: 2270.1, Max: 2464, Diff: 2463, Sum: 74914]

 [GC Worker Other (ms): Min: 0.0, Avg: 0.2, Max: 0.5, Diff: 0.5, Sum: 8.1]

 [GC Worker Total (ms): Min: 3821.2, Avg: 3821.8, Max: 3822.5, Diff: 1.3, Sum: 126118.4]

 [GC Worker End (ms): Min: 899827.7, Avg: 899827.9, Max: 899828.2, Diff: 0.5]

 [Queue Fixup (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]

 [Table Fixup (ms): Min: 0.0, Avg: 0.1, Max: 1.0, Diff: 1.0, Sum: 1.9]

[代码根修复：0.5毫秒]

[代码根清除：0.1毫秒]

[字符串重复数据消除修复：1.1毫秒，GC工作人员：33]

 [GC Worker Start (ms): Min: 3158.7, Avg: 3159.4, Max: 3159.8, Diff: 1.1]

 [Ext Root Scanning (ms): Min: 0.6, Avg: 1.1, Max: 2.7, Diff: 2.1, Sum: 35.9]

 [Update RS (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.1]

    [Processed Buffers: Min: 0, Avg: 0.1, Max: 2, Diff: 2, Sum: 4]

 [Scan RS (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.2]

 [Code Root Scanning (ms): Min: 0.0, Avg: 0.3, Max: 5.9, Diff: 5.9, Sum: 8.5]

 [Object Copy (ms): Min: 135.7, Avg: 141.1, Max: 141.5, Diff: 5.9, Sum: 4654.7]

 [Termination (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.7]

    [Termination Attempts: Min: 1, Avg: 9.1, Max: 15, Diff: 14, Sum: 301]

 [GC Worker Other (ms): Min: 0.0, Avg: 0.0, Max: 0.1, Diff: 0.1, Sum: 0.9]

 [GC Worker Total (ms): Min: 142.0, Avg: 142.5, Max: 143.1, Diff: 1.1, Sum: 4701.0]

 [GC Worker End (ms): Min: 3301.8, Avg: 3301.9, Max: 3301.9, Diff: 0.1]

 [Queue Fixup (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]

 [Table Fixup (ms): Min: 0.0, Avg: 0.0, Max: 0.7, Diff: 0.7, Sum: 0.7]

 [GC Worker Start (ms): Min: 896005.5, Avg: 896006.2, Max: 896006.6, Diff: 1.1]

 [Ext Root Scanning (ms): Min: 4.3, Avg: 5.3, Max: 8.4, Diff: 4.1, Sum: 175.2]

 [Update RS (ms): Min: 0.0, Avg: 0.2, Max: 0.8, Diff: 0.8, Sum: 7.6]

    [Processed Buffers: Min: 0, Avg: 1.3, Max: 6, Diff: 6, Sum: 44]

 [Scan RS (ms): Min: 2254.9, Avg: 2266.4, Max: 2268.2, Diff: 13.3, Sum: 74790.0]

 [Code Root Scanning (ms): Min: 0.0, Avg: 0.7, Max: 10.4, Diff: 10.4, Sum: 23.8]

 [Object Copy (ms): Min: 1535.2, Avg: 1537.7, Max: 1548.1, Diff: 13.0, Sum: 50745.7]

 [Termination (ms): Min: 0.0, Avg: 11.2, Max: 13.3, Diff: 13.2, Sum: 368.0]

    [Termination Attempts: Min: 1, Avg: 2270.1, Max: 2464, Diff: 2463, Sum: 74914]

 [GC Worker Other (ms): Min: 0.0, Avg: 0.2, Max: 0.5, Diff: 0.5, Sum: 8.1]

 [GC Worker Total (ms): Min: 3821.2, Avg: 3821.8, Max: 3822.5, Diff: 1.3, Sum: 126118.4]

 [GC Worker End (ms): Min: 899827.7, Avg: 899827.9, Max: 899828.2, Diff: 0.5]

 [Queue Fixup (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.0]

 [Table Fixup (ms): Min: 0.0, Avg: 0.1, Max: 1.0, Diff: 1.0, Sum: 1.9]

[清晰CT:4.7毫秒]

[其他：21.9毫秒]

 [Choose CSet: 0.0 ms]

 [Ref Proc: 8.5 ms]

 [Ref Enq: 0.9 ms]

 [Redirty Cards: 4.1 ms]

 [Humongous Register: 0.2 ms]

 [Humongous Reclaim: 0.0 ms]

 [Free CSet: 6.2 ms]

[伊甸园：81184.0M（81184.0M）->0.0B（71904.0M）幸存者：736.0M->10016.0M堆：83643.5M（160.0G）->11744.0M（160.0G）]

[次数：user=50.77 sys=10.33，real=3.85秒]

其中一个是显而易见的，它与元空间有关。我的意思是，当触发一个完整的GC时，初始阶段是

mark

我知道还有3种情况会触发标记阶段（如下所示）：

 1) IHOP is reached
 2) G1ReservePercent is reached
 3) a humongous allocation happens

标记阶段后发生的情况取决于几个参数，例如

mixed GCs

将取决于

G1HeapWastePercent

参数；但无论如何，

标记阶段后将触发年轻GC


第一点是一个巨大的分配是一个并发周期，您可以分析它是否以及何时这样做
第二点（来自您的评论）：我的意思是，一般来说，这是触发并发标记阶段的原因，而不是针对您的具体案例
但让我们看看您的日志（我稍微格式化了它）：
这说明了一些事情。您的伊甸园是80GB
，70GB
，其中有死物。因此，Eden
减少到71904.0M
，Survivor
变大到10016 M
。因为您已经设置了InitiatingHeapOccupencyPercent=70
，所以当Eden那么大时，这种情况永远不会发生，这个值永远不会达到70%。想一想，你会说：“当我占老一代总堆的70%时，开始一个标记阶段”；但你的伊甸园占了50%。。。这只是一个小小的观察
至于触发的原因-这是显而易见的：您的伊甸园已满（81184.0M（81184.0M）
）。至于为什么初始标记也？它总是作为年轻收藏的一部分触发
第三点
我不太明白你的意思。日志中明确指出，initial mark
，这是一个STW事件
，它做了一个young GC
感谢尤金的评论！关于3）发生大量分配，我有不同的想法。分配了许多巨大的反对意见（50+），但它不会触发如此多的初始标记。关于2）达到保留百分比，我也有不同的想法。在JVM启动之初，最大使用的堆是80G（总堆是160G），gc日志中没有到空间溢出。关于“我的意思是当触发完整gc时，初始阶段是mark”，我认为这是并发标记周期，而不是完整gc。我的假设是基于gc原因“[gc暂停（元数据gc阈值）（年轻）（初始标记）”，请随时告诉我是否有任何不同的想法，谢谢！谢谢您的评论，关于“第三点”，您提到“发生了大量分配”将触发标记阶段。我不认为是这样，这是我的观点，希望它澄清。Thx！@RoyZhang你不认为你的情况是这样的，对吗？意思是你不认为你提交的日志（包含（G1疏散暂停）（年轻）（initia