jvm调优案例

JVM调优

JVM 收集器

默认使用串行收集器&＃xff0c; 单个cpu时适用吞吐收集器&＃xff08;throughput collector&＃xff09;&＃xff1a;命令行参数&＃xff1a;-XX:&＃43;UseParallelGC。在新生代使用并行清除收集策略&＃xff0c;在旧生代和默认收集器相同。
适用&＃xff1a;a、拥有2个以上cpu&＃xff0c; b、临时对象较多的程序
-XX:ParallelGCThreads 并行收集线程数量&＃xff0c;最好和cpu数量相当并发收集器&＃xff08;concurrent low pause collector&＃xff09;&＃xff1a;命令行参数&＃xff1a;-XX:&＃43;UseConcMarkSweepGC。在旧生代使用并发收集策略&＃xff0c;大部分收集工作都是和应用并发进行的&＃xff0c;在进行收集的时候&＃xff0c;应用的暂停时间很短。默认配套打开 -XX:&＃43;UseParNewGC&＃xff0c;会在新生代使用并行复制收集。
适用&＃xff1a;a、拥有多个cpu&＃xff0c; b、老对象较多的程序

-XX:&＃43;UseCMSCompactAtFullCollection&＃xff1a;打开对年老代的压缩。可能会影响性能&＃xff0c;但是可以消除碎片
-XX:&＃43;UseFastAccessorMethods 原始类型的快速优化
-XX:SurvivorRatio 新生区中&＃xff0c;eden&survivor的比例&＃xff0c;设置为8
-XX:TargetSurvivorRatio 生存区需要做垃圾回收的比例值&＃xff0c;默认为50%&＃xff0c;设置高些可以更好的利用该区


设置jvm参数

$ java -jar -XX:MetaspaceSize&＃61;128m -XX:MaxMetaspaceSize&＃61;128m -Xms1024m -Xmx1024m -Xmn256m -Xss256k -XX:SurvivorRatio&＃61;8 -XX:&＃43;UseConcMarkSweepGC newframe-1.0.0.jar$JAVA_ARGS
.&＃61;
"
-Dresin.home&＃61;$SERVER_ROOT
-server
-Xmx3000M
-Xms3000M
-Xmn600M
-XX:PermSize&＃61;500M
-XX:MaxPermSize&＃61;500M
-Xss256K
-XX:&＃43;DisableExplicitGC
-XX:SurvivorRatio&＃61;1
-XX:&＃43;UseConcMarkSweepGC
-XX:&＃43;UseParNewGC
-XX:&＃43;CMSParallelRemarkEnabled
-XX:&＃43;UseCMSCompactAtFullCollection
-XX:CMSFullGCsBeforeCompaction&＃61;0
-XX:&＃43;CMSClassUnloadingEnabled
-XX:LargePageSizeInBytes&＃61;128M
-XX:&＃43;UseFastAccessorMethods
-XX:&＃43;UseCMSInitiatingOccupancyOnly
-XX:CMSInitiatingOccupancyFraction&＃61;70
-XX:SoftRefLRUPolicyMSPerMB&＃61;0
-XX:&＃43;PrintClassHistogram
-XX:&＃43;PrintGCDetails
-XX:&＃43;PrintGCTimeStamps
-XX:&＃43;PrintHeapAtGC
-Xloggc:log/gc.log
";


调优策略

JVM各个参数之间有一个平衡性的&＃xff0c;另外根据业务类型和实际的运行环境都有不一样的效果。但是有些约定俗成的规定还是值得借鉴的&＃xff1a;
1&＃xff09;堆内存不超过物理内存的3/4
2&＃xff09;年轻代的大小不超过堆内存的3/8
3&＃xff09;CMSInitiatingOccupancyFraction一般不低于70%

(Xmx-Xmn)*(1-CMSInitiatingOccupancyFraction/100)>&＃61;(Xmn-Xmn/(SurvivorRatior&＃43;2))

参考参数:

xms

xmn

survivor

xmn

gc

6G

6G

4

2G

CMSInitiatingOccupancyFraction&＃61;70

6G

6G

3

1.75G

CMSInitiatingOccupancyFraction&＃61;70

工具使用

查看线程cpu占用1

[root&＃64;localhost ~]# ps p 6515 -L -o pcpu,pid,tid,time,tname,cmd --sort pcpu
%CPU PID TID TIME TTY CMD 0.0 6515 6515 00:00:00 pts/1 java -jar xxl-job-admin-2.0.2-SNAPSHOT.jar 0.0 6515 6523 00:00:04 pts/1 java -jar xxl-job-admin-2.0.2-SNAPSHOT.jar 0.0 6515 6529 00:00:00 pts/1 java -jar xxl-job-admin-2.0.2-SNAPSHOT.jar


查看线程cpu占用2

[root&＃64;localhost ~]# ps -mp 6515 -o THREAD,tid,time
USER %CPU PRI SCNT WCHAN USER SYSTEM TID TIME
root 0.3 - - - - - - 00:00:58
root 0.0 19 - futex_ - - 6515 00:00:00
root 0.0 19 - futex_ - - 6523 00:00:04
root 0.0 19 - futex_ - - 6529 00:00:00
root 0.0 19 - futex_ - - 6530 00:00:00


找到的线程ID转换为16进制格式

[root&＃64;localhost ~]# printf "%x
" 6523
197b


打印线程的堆栈信息

[root&＃64;localhost ~]# jstack 6515 | grep 197b -A 30
"DestroyJavaVM" #94 prio&＃61;5 os_prio&＃61;0 tid&＃61;0x00007f83f004b000 nid&＃61;0x197b waiting on condition [0x0000000000000000] java.lang.Thread.State: RUNNABLE"http-nio-9988-AsyncTimeout" #92 daemon prio&＃61;5 os_prio&＃61;0 tid&＃61;0x00007f83f0758000 nid&＃61;0x19e4 waiting on condition [0x00007f8352bee000] java.lang.Thread.State: TIMED_WAITING (sleeping) at java.lang.Thread.sleep(Native Method) at org.apache.coyote.AbstractProtocol$AsyncTimeout.run(AbstractProtocol.java:1149) at java.lang.Thread.run(Thread.java:748)"http-nio-9988-Acceptor-0" #91 daemon prio&＃61;5 os_prio&＃61;0 tid&＃61;0x00007f83f0382800 nid&＃61;0x19e3 runnable [0x00007f8352cef000] java.lang.Thread.State: RUNNABLE at sun.nio.ch.ServerSocketChannelImpl.accept0(Native Method) at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:422) at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:250) - locked <0x00000006c7c2ada0> (a java.lang.Object) at org.apache.tomcat.util.net.NioEndpoint$Acceptor.run(NioEndpoint.java:482) at java.lang.Thread.run(Thread.java:748)"http-nio-9988-ClientPoller-1" #90 daemon prio&＃61;5 os_prio&＃61;0 tid&＃61;0x00007f83f11d1000 nid&＃61;0x19e2 runnable [0x00007f8352df0000] java.lang.Thread.State: RUNNABLE at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method) at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:269) at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:93) at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86) - locked <0x00000006c7c2b548> (a sun.nio.ch.Util$3) - locked <0x00000006c7c2b538> (a java.util.Collections$UnmodifiableSet) - locked <0x00000006c7c2b400> (a sun.nio.ch.EPollSelectorImpl) at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97) at org.apache.tomcat.util.net.NioEndpoint$Poller.run(NioEndpoint.java:825) at java.lang.Thread.run(Thread.java:748)


执行jmap把当前的堆dump下来

jmap -dump:live,format&＃61;b,file&＃61;dump.hprof 6515


将dump.hprof文件使用VisualVM来打开

SpringBoot TOMCAT调优

tomcat参数说明

maxThreads 客户请求最大线程数
minSpareThreads Tomcat初始化时创建的 socket 线程数
maxSpareThreads Tomcat连接器的最大空闲 socket 线程数
enableLookups 若设为true, 则支持域名解析&＃xff0c;可把 ip 地址解析为主机名
redirectPort 在需要基于安全通道的场合&＃xff0c;把客户请求转发到基于SSL 的 redirectPort 端口
acceptAccount 监听端口队列最大数&＃xff0c;满了之后客户请求会被拒绝&＃xff08;不能小于maxSpareThreads &＃xff09;
connectionTimeout 连接超时
minProcessors 服务器创建时的最小处理线程数
maxProcessors 服务器同时最大处理线程数
URIEncoding URL统一编码


tomcat在springboot上的配置ServerProperties.java --> application.properties

server.tomcat.accesslog.enabled &＃61;
server.tomcat.accesslog.pattern &＃61;
server.tomcat.accesslog.directory &＃61;
server.tomcat.accesslog.prefix &＃61;
server.tomcat.accesslog.suffix &＃61;
server.tomcat.accesslog.rotate &＃61;
server.tomcat.accesslog.renameOnRotate &＃61;
server.tomcat.accesslog.requestAttributesEnabled&＃61;
server.tomcat.accesslog.buffered &＃61;
server.tomcat.internalProxies &＃61;
server.tomcat.protocolHeader &＃61;
server.tomcat.protocolHeaderHttpsValue &＃61;
server.tomcat.portHeader &＃61;
server.tomcat.remoteIpHeader&＃61;
server.tomcat.basedir &＃61;
server.tomcat.backgroundProcessorDelay &＃61;
server.tomcat.maxThreads &＃61;
server.tomcat.minSpareThreads &＃61;
server.tomcat.maxHttpPostSize &＃61;
server.tomcat.maxHttpHeaderSize &＃61;
server.tomcat.redirectContextRoot &＃61;
server.tomcat.uriEncoding &＃61;
server.tomcat.maxConnections &＃61;
server.tomcat.acceptCount &＃61;
server.tomcat.additionalTldSkipPatterns &＃61;


tomcat在application.yml上的配置

server: tomcat: min-spare-threads: 20 max-threads: 100 connection-timeout: 5000


参考:
1.JAVAEE文档:https://www.oracle.com/technetwork/java/javase/tech/vmoptions-jsp-140102.html
2.深入理解JAVA虚拟机(内存模型&＃43;GC算法&＃43;JVM调优):https://www.cnblogs.com/yueshutong/p/9768298.html
3.JVM调优实践:https://blog.wangqi.love/articles/Java/JVM%E8%B0%83%E4%BC%98%E5%AE%9E%E8%B7%B5.html
4.JVM解读-性能调优实例:https://www.jianshu.com/p/2c4b091deaa3
5.扩容&＃xff1f;先尝试一下JVM调优吧:https://sq.163yun.com/blog/article/211688346067283968
6.JVM调优参数简介、调优目标及调优经验https://blog.csdn.net/jisuanjiguoba/article/details/80176223
7.jvm优化必知系列——监控工具https://juejin.im/post/59e6c1f26fb9a0451c397a8c
8.JVM活学活用——优化springboothttps://cloud.tencent.com/developer/article/1089954
9.SpringBoot服务器压测对比(jetty、tomcat、undertow)https://my.oschina.net/shyloveliyi/blog/2980868