关注公众号：Java架构师联盟，每日更新技术好文

部分资料已经上传到我的git仓库中：有需要的可以下载

最近因为工作和面试的原因（大boss也不知道咋想的，把面试的任务给了我一部分，我之后是总监面，要了命了）那就跟随市场潮流吧，市场上什么比较火热，我就用什么技术问白，正好公司业务中最近也用到了jvm的相关的内容，所以也算是自己回忆复习，也算是总结吧，我把常用的jvm调优的参数进行整理，并且在最后，我将jvm所涉及的知识点进行了详细的整理

Sun JDK 监控和故障处理工具

常用命令：

1. jps -l 查询LVMID,及主类的名称 C:\Users\Harry>jps -l 11856 com.ssm.common.jvm.JvmTest 14368 com.ddc.template.TemplateApplication 16848 19664 6640 org.jetbrains.jps.cmdline.Launcher 7732 sun.tools.jps.Jps 2168 org.apache.zookeeper.server.quorum.QuorumPeerMain 2. jps -v 输出虚拟机进程参数 C:\Users\Harry>jps -v 11856 JvmTest -agentlib:jdwp=transport=dt_socket,suspend=y,address=localhost:49232 -verbose:gc -Xms20M -Xmx20M -Xmn10M -XX:+PrintGCDetails -XX:SurvivorRatio=8 -Dfile.encoding=utf8 3. jstat -gc 11856 250 5 每250毫秒查询一次进程11856垃圾收集情况状况，一共查询5次 C:\Users\Harry>jstat -gc 11856 250 20 S0C S1C S0U S1U EC EU OC OU MC MU CCSC CCSU YGC YGCT FGC FGCT GCT 1024.0 1024.0 0.0 0.0 8192.0 7619.8 10240.0 0.0 4480.0 780.5 384.0 75.8 0 0.000 0 0.000 0.000 1024.0 1024.0 0.0 0.0 8192.0 7619.8 10240.0 0.0 4480.0 780.5 384.0 75.8 0 0.000 0 0.000 0.000 1024.0 1024.0 0.0 0.0 8192.0 7619.8 10240.0 0.0 4480.0 780.5 384.0 75.8 0 0.000 0 0.000 0.000 1024.0 1024.0 0.0 0.0 8192.0 7619.8 10240.0 0.0 4480.0 780.5 384.0 75.8 0 0.000 0 0.000 0.000 1024.0 1024.0 0.0 0.0 8192.0 7619.8 10240.0 0.0 4480.0 780.5 384.0 75.8 0 0.000 0 0.000 0.000 4. jstat -gc 11856 只查询一次 C:\Users\Harry>jstat -gc 11856 S0C S1C S0U S1U EC EU OC OU MC MU CCSC CCSU YGC YGCT FGC FGCT GCT 1024.0 1024.0 0.0 0.0 8192.0 7619.8 10240.0 0.0 4480.0 780.5 384.0 75.8 0 0.000 0 0.000 0.000 5. jstat -gcutil 11856 查询各JVM内存使用百分比 C:\Users\Harry>jstat -gcutil 11856 S0 S1 E O M CCS YGC YGCT FGC FGCT GCT 0.00 0.00 93.01 0.00 17.42 19.75 0 0.000 0 0.000 0.000 6. jstat -gcnew 11856 查询新生代GC状况 C:\Users\Harry>jstat -gcnew 11856 S0C S1C S0U S1U TT MTT DSS EC EU YGC YGCT 1024.0 1024.0 0.0 0.0 15 15 0.0 8192.0 7619.8 0 0.000 7. jstat -gcold 11856 查询老年代GC状况 C:\Users\Harry>jstat -gcold 11856 MC MU CCSC CCSU OC OU YGC FGC FGCT GCT 4480.0 780.5 384.0 75.8 10240.0 0.0 0 0 0.000 0.000 8. jinfo -flag CMSInitiatingOccupancyFraction 11856 查询JVM参数的值 C:\Users\Harry>jinfo -flag CMSInitiatingOccupancyFraction 11856 -XX:CMSInitiatingOccupancyFraction=-1 9. jinfo -sysprops 11856 可以把System.getProperties()信息打印出来 C:\Users\Harry>jinfo -sysprops 11856 Attaching to process ID 11856, please wait... Debugger attached successfully. Server compiler detected. JVM version is 25.92-b14 java.runtime.name = Java(TM) SE Runtime Environment java.vm.version = 25.92-b14 ...... 10. jmap -dump:format=b,file=eclipse.bin 11856 生成java堆转储快照 C:\Users\Harry>jmap -dump:format=b,file=eclipse.bin 11856 Dumping heap to C:\Users\Harry\eclipse.bin ... Heap dump file created 11. jhat eclipse.bin 分析dump文件，浏览器中访问http://localhost:7000 C:\Users\Harry>jhat eclipse.bin Reading from eclipse.bin... Dump file created Sun Jul 22 11:55:08 CST 2018 Snapshot read, resolving... Resolving 11914 objects... Chasing references, expect 2 dots.. Eliminating duplicate references.. Snapshot resolved. Started HTTP server on port 7000 Server is ready. 12. jmap -heap 11856 查看堆中jvm参数情况 Attaching to process ID 11856, please wait... Debugger attached successfully. Server compiler detected. JVM version is 25.131-b11 using thread-local object allocation. Parallel GC with 8 thread(s) Heap Configuration: MinHeapFreeRatio = 0 MaxHeapFreeRatio = 100 MaxHeapSize = 1073741824 (1024.0MB) NewSize = 357564416 (341.0MB) MaxNewSize = 357564416 (341.0MB) OldSize = 716177408 (683.0MB) NewRatio = 2 SurvivorRatio = 8 MetaspaceSize = 21807104 (20.796875MB) CompressedClassSpaceSize = 1073741824 (1024.0MB) MaxMetaspaceSize = 17592186044415 MB G1HeapRegionSize = 0 (0.0MB) Heap Usage: PS Young Generation Eden Space: capacity = 310902784 (296.5MB) used = 90540600 (86.34624481201172MB) free = 220362184 (210.15375518798828MB) 29.121836361555385% used From Space: capacity = 23068672 (22.0MB) used = 11927744 (11.37518310546875MB) free = 11140928 (10.62481689453125MB) 51.70537775213068% used To Space: capacity = 22544384 (21.5MB) used = 0 (0.0MB) free = 22544384 (21.5MB) 0.0% used PS Old Generation capacity = 716177408 (683.0MB) used = 82475416 (78.6546859741211MB) free = 633701992 (604.3453140258789MB) 11.516059439842035% used 13. jmap -dump:live,format=b,file=heap.hprof 11856 将heap.hprof传输出来到window电脑上使用mat工具分析。 14. jhat -heap 11856 显示java堆详细信息，如使用哪种回收器、参数配置、分代状况等，只在linux平台才可以测试 15. jstack -l 11856 除堆栈外，显示锁的附加信息 "Finalizer" #3 daemon prio=8 os_prio=1 tid=0x00000000152da800 nid=0x18b4 in Object.wait() [0x000000001664e000] java.lang.Thread.State: WAITING (on object monitor) at java.lang.Object.wait(Native Method) - waiting on <0x00000000ff608ee0> (a java.lang.ref.ReferenceQueue$Lock) at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143) - locked <0x00000000ff608ee0> (a java.lang.ref.ReferenceQueue$Lock) at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:164) at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:209) Locked ownable synchronizers: - None "Reference Handler" #2 daemon prio=10 os_prio=2 tid=0x00000000152b9000 nid=0x444c in Object.wait() [0x000000001654f000] java.lang.Thread.State: WAITING (on object monitor) at java.lang.Object.wait(Native Method) - waiting on <0x00000000ff606b50> (a java.lang.ref.Reference$Lock) at java.lang.Object.wait(Object.java:502) at java.lang.ref.Reference.tryHandlePending(Reference.java:191) - locked <0x00000000ff606b50> (a java.lang.ref.Reference$Lock) at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153) Locked ownable synchronizers: - None