这是一个springboot框架的后台任务，每半个小时运行一次。
最开始是在物理机上运行，每次启动进程，运行完进程关闭。所以并不涉及到垃圾回收的问题。
后来公司统一决策，后台任务全部接入公司的xxx-job衍生版(自己公司封装了一下)；并且放在docke容器中运行。所以每半小时运行一次后进程并不关停。
docker 容器默认是2核5G的。在项目刚迁移没多久就开始报警，cpu 内存等超限（超过设定的80%）。然后就升级为8核/10G。平稳的运行了一段时间（就是没报警）。
不过近期又开始报cpu超限。然后决定看一下。
可以看到每次执行任务是cpu基本都100%了。
top命令看一下配置。不过这个是平时（非任务运行时间段）的状态。供各位看官参考。
top - 10:42:57 up 320 days, 14:25, 1 user, load average: 14.75, 14.96, 15.96
Tasks: 15 total, 1 running, 14 sleeping, 0 stopped, 0 zombie
%Cpu(s): 24.6 us, 5.3 sy, 0.0 ni, 68.2 id, 0.0 wa, 0.0 hi, 1.9 si, 0.0 st
KiB Mem : 26351976+total, 11896940 free, 91484688 used, 16013814+buff/cache
KiB Swap: 0 total, 0 free, 0 used. 16701171+avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1 work 20 0 49884 36300 2980 S 3.3 0.0 2518:18 sh
260471 root 20 0 1064896 30096 1636 S 0.7 0.0 108:16.93 mount.scffs
1147 work 20 0 19.093g 5.859g 10552 S 0.3 2.3 12458:37 java
682 root 20 0 27756 2744 2072 S 0.0 0.0 1:53.82 crond
1062 root 20 0 105428 2796 1820 S 0.0 0.0 0:01.06 sshd
1085 root 20 0 273708 4368 2916 S 0.0 0.0 1:14.98 rsyslogd
1124 work 20 0 19696 6136 2964 S 0.0 0.0 5:02.65 sh
314840 root 20 0 141532 8924 7648 S 0.0 0.0 0:00.01 sshd
314842 work 20 0 141532 3876 2600 S 0.0 0.0 0:00.11 sshd
314843 work 20 0 16888 3736 3288 S 0.0 0.0 0:00.29 bash
317945 work 20 0 57000 4104 3540 R 0.0 0.0 0:00.00 top
317950 work 20 0 9396 660 592 S 0.0 0.0 0:00.00 sleep
317952 work 20 0 9396 636 564 S 0.0 0.0 0:00.00 sleep
356861 root 20 0 1830028 15144 7620 S 0.0 0.0 16:04.52 monitor-agent
690207 root 20 0 1667604 9280 4992 S 0.0 0.0 54:20.65 58agent
ps命令看一下启动参数，这里说下jdk版本是1.8。
ps -ef | grep java
work 1147 1 5 May25 ? 8-15:38:37 java -Xmx5324M -Xms5324M -Xmn2048M -XX:MaxMetaspaceSize=256M -XX:MetaspaceSize=256M -jar *.jar --spring.profiles.active=prod
work 318823 314843 0 10:56 pts/0 00:00:00 grep --color java
- 进程号：1147
- 堆内存：5g
- 年轻代: 2g
- 元空间：256M
其它都是默认配置了。
jmap 看一下堆内存信息
jmap -heap 1147
Attaching to process ID 1147, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.45-b02
using thread-local object allocation.
Parallel GC with 18 thread(s)
Heap Configuration:
MinHeapFreeRatio = 0
MaxHeapFreeRatio = 100
MaxHeapSize = 5582618624 (5324.0MB)
NewSize = 2147483648 (2048.0MB)
MaxNewSize = 2147483648 (2048.0MB)
OldSize = 3435134976 (3276.0MB)
NewRatio = 2
SurvivorRatio = 8
MetaspaceSize = 268435456 (256.0MB)
CompressedClassSpaceSize = 1073741824 (1024.0MB)
MaxMetaspaceSize = 268435456 (256.0MB)
G1HeapRegionSize = 0 (0.0MB)
Heap Usage:
PS Young Generation
Eden Space:
capacity = 2107637760 (2010.0MB)
used = 1419086080 (1353.345947265625MB)
free = 688551680 (656.654052734375MB)
67.3306441425684% used
From Space:
capacity = 20447232 (19.5MB)
used = 0 (0.0MB)
free = 20447232 (19.5MB)
0.0% used
To Space:
capacity = 19398656 (18.5MB)
used = 0 (0.0MB)
free = 19398656 (18.5MB)
0.0% used
PS Old Generation
capacity = 3435134976 (3276.0MB)
used = 3434964768 (3275.837677001953MB)
free = 170208 (0.162322998046875MB)
99.99504508552971% used
24442 interned Strings occupying 3001848 bytes.
- 垃圾回收器为jdk8的默认回收器 Parallel。
- 新生代和老年代配置分别为 2G和3G。和上面配置一样。
- 伊甸园区基本把年轻代全占了和存活区的并不符合默认配置8:1。 且存活区没有使用。
- 老年代几乎百分百。
$ jps
1383 jar
1609 Jps
$ jmap -heap 1383
Attaching to process ID 1383, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.45-b02
using thread-local object allocation.
Parallel GC with 18 thread(s)
Heap Configuration:
MinHeapFreeRatio = 0
MaxHeapFreeRatio = 100
MaxHeapSize = 5582618624 (5324.0MB)
NewSize = 2147483648 (2048.0MB)
MaxNewSize = 2147483648 (2048.0MB)
OldSize = 3435134976 (3276.0MB)
NewRatio = 2
SurvivorRatio = 8
MetaspaceSize = 268435456 (256.0MB)
CompressedClassSpaceSize = 1073741824 (1024.0MB)
MaxMetaspaceSize = 268435456 (256.0MB)
G1HeapRegionSize = 0 (0.0MB)
Heap Usage:
PS Young Generation
Eden Space:
capacity = 1610612736 (1536.0MB)
used = 228417520 (217.83592224121094MB)
free = 1382195216 (1318.164077758789MB)
14.182026187578836% used
From Space:
capacity = 268435456 (256.0MB)
used = 27291432 (26.027137756347656MB)
free = 241144024 (229.97286224365234MB)
10.166850686073303% used
To Space:
capacity = 268435456 (256.0MB)
used = 0 (0.0MB)
free = 268435456 (256.0MB)
0.0% used
PS Old Generation
capacity = 3435134976 (3276.0MB)
used = 114704 (0.1093902587890625MB)
free = 3435020272 (3275.890609741211MB)
0.0033391409886771215% used
22021 interned Strings occupying 2657728 bytes.
初始化状态下新生代的内存占比达到默认比值数。
根据上面信息，因为存活区是0（运行好长时间了）。判断每次minor GC时。对象全部放到了老年代。
那么那些情况下对象会从年轻代到老年代呢?
特意等到任务执行前十几秒运行jstat命令查看垃圾回收信息。没5秒打印一次GC信息。
$ jstat -gcutil 1147 5000
S0 S1 E O M CCS YGC YGCT FGC FGCT GCT
0.00 0.00 63.71 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 63.75 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 63.75 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 63.75 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 64.62 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 66.05 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 72.63 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 78.39 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 84.68 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 90.40 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 95.83 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 97.83 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 98.40 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 98.73 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 98.73 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 99.01 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 99.30 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 99.59 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 99.59 100.00 96.39 94.62 3255 84.738 4296 82706.283 82791.022
0.00 0.00 100.00 100.00 96.39 94.62 3255 84.738 4297 82706.283 82791.022
0.00 0.00 100.00 100.00 96.39 94.62 3255 84.738 4297 82706.283 82791.022
0.00 0.00 100.00 100.00 96.39 94.62 3255 84.738 4297 82706.283 82791.022
0.00 0.00 100.00 100.00 96.39 94.62 3255 84.738 4297 82706.283 82791.022
0.00 0.00 64.62 100.00 96.40 94.64 3255 84.738 4297 82726.704 82811.443
0.00 0.00 70.94 100.00 96.40 94.64 3255 84.738 4297 82726.704 82811.443
0.00 0.00 100.00 100.00 96.40 94.64 3255 84.738 4298 82726.704 82811.443
0.00 0.00 100.00 100.00 96.40 94.64 3255 84.738 4298 82726.704 82811.443
0.00 0.00 100.00 100.00 96.40 94.64 3255 84.738 4298 82726.704 82811.443
0.00 0.00 100.00 100.00 96.40 94.64 3255 84.738 4298 82726.704 82811.443
0.00 0.00 68.29 100.00 96.42 94.65 3255 84.738 4298 82748.130 82832.868
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4299 82748.130 82832.868
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4299 82748.130 82832.868
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4299 82748.130 82832.868
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4299 82748.130 82832.868
0.00 0.00 83.73 100.00 96.42 94.65 3255 84.738 4299 82769.230 82853.968
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4300 82769.230 82853.968
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4300 82769.230 82853.968
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4300 82769.230 82853.968
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4300 82769.230 82853.968
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4301 82790.289 82875.028
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4301 82790.289 82875.028
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4301 82790.289 82875.028
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4301 82790.289 82875.028
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4301 82790.289 82875.028
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4302 82811.815 82896.554
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4302 82811.815 82896.554
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4302 82811.815 82896.554
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4302 82811.815 82896.554
0.00 0.00 61.63 100.00 96.42 94.65 3255 84.738 4302 82832.864 82917.602
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4303 82832.864 82917.602
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4303 82832.864 82917.602
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4303 82832.864 82917.602
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4303 82832.864 82917.602
0.00 0.00 73.89 100.00 96.42 94.65 3255 84.738 4303 82854.499 82939.237
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4304 82854.499 82939.237
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4304 82854.499 82939.237
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4304 82854.499 82939.237
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4304 82854.499 82939.237
0.00 0.00 94.27 100.00 96.42 94.65 3255 84.738 4304 82875.563 82960.302
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4305 82875.563 82960.302
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4305 82875.563 82960.302
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4305 82875.563 82960.302
0.00 0.00 100.00 100.00 96.42 94.65 3255 84.738 4305 82875.563 82960.302
0.00 0.00 67.20 100.00 96.42 94.65 3255 84.738 4305 82896.061 82980.800
0.00 0.00 67.24 100.00 96.42 94.65 3255 84.738 4305 82896.061 82980.800
0.00 0.00 67.24 100.00 96.42 94.65 3255 84.738 4305 82896.061 82980.800
0.00 0.00 67.24 100.00 96.42 94.65 3255 84.738 4305 82896.061 82980.800
0.00 0.00 67.24 100.00 96.42 94.65 3255 84.738 4305 82896.061 82980.800
0.00 0.00 67.24 100.00 96.42 94.65 3255 84.738 4305 82896.061 82980.800