# G1CG调优
- https://cloud.tencent.com/developer/article/1518229
- -XX:+UseG1GC -XX:+UseStringDeduplication
- -Xms2g -Xmx2g
  -XX:+UseG1GC -XX:MaxGCPauseMillis=20 -XX:G1HeapRegionSize=1m -XX:G1MixedGCCountTarget=10
  -Xloggc:/data/server/${app}/gc.log -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintGCApplicationStoppedTime
- -Xms2g -Xmx2g
  -XX:+UseG1GC
  -XX:MaxGCPauseMillis=100 // 调大停顿时间
  -XX:G1HeapRegionSize=2M  # 调大region的大小来减少大对象占用的region数
  -XX:MaxTenuringThreshold=5
  -XX:InitiatingHeapOccupancyPercent=40  #手动设置IHOP。
  -XX:ConcGCThreads=4 //当前核心数的一半
  -XX:+UseStringDeduplication
  -XX:AutoBoxCacheMax=20000
  -XX:MetaspaceSize=128m -XX:MaxMetaspaceSize=256m
  -XX:+PrintPromotionFailure
  -XX:+HeapDumpOnOutOfMemoryError
  -XX:HeapDumpPath=./
  -Xlog:gc*:./gc-myapp.log
  -XX:+DisableExplicitGC //禁止显示手动GC，如果系统使用了堆外内存就不要禁用
  -XX:G1MixedGCCountTarget=10 // 把old区的回收分布到更多次GC当中
- https://zhuanlan.zhihu.com/p/444564414

## 启动参数
```shell
java -server 
-XX:+UseContainerSupport 
-XX:InitialRAMPercentage=70.0 
-XX:MaxRAMPercentage=70.0 
-XX:+UseG1GC 
-XX:MaxGCPauseMillis=20 
-XX:G1HeapRegionSize=1M 
-XX:InitiatingHeapOccupancyPercent=45 
-XX:+UseStringDeduplication
-Ddruid.mysql.usePingMethod=false 
-javaagent:/app/skywalking-agent/skywalking-agent.jar 
-Dskywalking.agent.service_name=qifu-saas-wms-prod 
-Dskywalking.collector.backend_service=oap.qifu.svc:11800 
-jar 
-javaagent:/app/jmx_prometheus_javaagent-0.20.0.jar=8088:/app/jmx_exporter.yaml 
/app/qifu-saas-wms-service-1.0.13.jar 
--spring.config.location=/app/config/bootstrap.yml
```
### 参数说明
- https://www.cnblogs.com/yu007/p/17900844.html 
- 容器环境替代 `-Xmx -Xms`: 
- ```shell
  -XX:+UseContainerSupport 
  -XX:InitialRAMPercentage=70.0 
  -XX:MaxRAMPercentage=70.0 
  ```