--- url: /notes/生产环境/oom-排查/index.md --- [怎么分析 JVM 当前的内存占用情况？OOM 后怎么分析？ - 后端场景面试题 - 面试鸭 - 程序员求职面试刷题神器](https://www.mianshiya.com/bank/1795650132375805954/question/1818990174270726145#heading-0) ## jstat ```sh jstat -gc 1000 10 ``` ![image-20250331093434738](https://note-1259190304.cos.ap-chengdu.myqcloud.com/noteimage-20250331093434738.png) ```sh S0C S1C S0U S1U EC EU OC OU MC MU CCSC CCSU YGC YGCT FGC FGCT GCT 1536.0 1536.0 0.0 0.0 30720.0 1024.0 708608.0 2048.0 44800.0 43712.6 4864.0 4096.0 4 0.072 1 0.015 0.087 1536.0 1536.0 0.0 0.0 30720.0 2048.0 708608.0 2048.0 44800.0 43712.6 4864.0 4096.0 4 0.072 1 0.015 0.087 1536.0 1536.0 0.0 0.0 30720.0 3072.0 708608.0 2048.0 44800.0 43712.6 4864.0 4096.0 4 0.072 1 0.015 0.087 ``` ![image-20250331093503071](https://note-1259190304.cos.ap-chengdu.myqcloud.com/noteimage-20250331093503071.png) ## jmap ```sh jmap -heap ``` ```sh Attaching to process ID 1234, please wait... Debugger attached successfully. Server compiler detected. JVM version is 25.131-b11 using parallel threads in the new generation. using thread-local object allocation. Concurrent Mark-Sweep GC Heap Configuration: MinHeapFreeRatio = 40 MaxHeapFreeRatio = 70 MaxHeapSize = 1048576000 (1000.0MB) NewSize = 1310720 (1.25MB) MaxNewSize = 17592186044415 MB OldSize = 8388608 (8.0MB) NewRatio = 2 SurvivorRatio = 8 MetaspaceSize = 21807104 (20.796875MB) CompressedClassSpaceSize = 1073741824 (1024.0MB) MaxMetaspaceSize = 17592186044415 MB G1HeapRegionSize = 0 (0.0MB) Heap Usage: New Generation (Eden + 1 Survivor Space): capacity = 46989312 (44.8125MB) used = 14364528 (13.697036743164062MB) free = 32624784 (31.115463256835938MB) 30.57471507400737% used Eden Space: capacity = 41943040 (40.0MB) used = 12058624 (11.5MB) free = 29884416 (28.5MB) 28.769444942474365% used From Space: capacity = 5036288 (4.8046875MB) used = 2305904 (2.1997528076171875MB) free = 2730384 (2.6049346923828125MB) 45.8012652387619% used To Space: capacity = 5036288 (4.8046875MB) used = 0 (0.0MB) free = 5036288 (4.8046875MB) 0.0% used concurrent mark-sweep generation: capacity = 100663296 (96.0MB) used = 1433600 (1.3671875MB) free = 99229696 (94.6328125MB) 1.4241612307230632% used 10764 interned Strings occupying 826944 bytes. ``` ![image-20250331093541171](https://note-1259190304.cos.ap-chengdu.myqcloud.com/noteimage-20250331093541171.png) ## arthas ```sh $ dashboard ID NAME GROUP PRIORI STATE %CPU TIME INTERRU DAEMON 17 pool-2-thread-1 system 5 WAITIN 67 0:0 false false 27 Timer-for-arthas-dashb system 10 RUNNAB 32 0:0 false true 11 AsyncAppender-Worker-a system 9 WAITIN 0 0:0 false true 9 Attach Listener system 9 RUNNAB 0 0:0 false true 3 Finalizer system 8 WAITIN 0 0:0 false true 2 Reference Handler system 10 WAITIN 0 0:0 false true 4 Signal Dispatcher system 9 RUNNAB 0 0:0 false true 26 as-command-execute-dae system 10 TIMED_ 0 0:0 false true 13 job-timeout system 9 TIMED_ 0 0:0 false true 1 main main 5 TIMED_ 0 0:0 false false 14 nioEventLoopGroup-2-1 system 10 RUNNAB 0 0:0 false false 18 nioEventLoopGroup-2-2 system 10 RUNNAB 0 0:0 false false 23 nioEventLoopGroup-2-3 system 10 RUNNAB 0 0:0 false false 15 nioEventLoopGroup-3-1 system 10 RUNNAB 0 0:0 false false Memory used total max usage GC heap 32M 155M 1820M 1.77% gc.ps_scavenge.count 4 ps_eden_space 14M 65M 672M 2.21% gc.ps_scavenge.time(m 166 ps_survivor_space 4M 5M 5M s) ps_old_gen 12M 85M 1365M 0.91% gc.ps_marksweep.count 0 nonheap 20M 23M -1 gc.ps_marksweep.time( 0 code_cache 3M 5M 240M 1.32% ms) Runtime os.name Mac OS X os.version 10.13.4 java.version 1.8.0_162 java.home /Library/Java/JavaVir tualMachines/jdk1.8.0 _162.jdk/Contents/Hom e/jre ``` ![image-20250331093637670](https://note-1259190304.cos.ap-chengdu.myqcloud.com/noteimage-20250331093637670.png) ## OOM分析 ### 1.使用jmap生成堆转储文件 ```sh jmap -dump:format=b,file=heap_dump.hprof ``` ![image-20250331093743794](https://note-1259190304.cos.ap-chengdu.myqcloud.com/noteimage-20250331093743794.png) ```sh -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/tmp/heapdump.hprof ``` ### 2.使用工具分析堆转储文件 ![image-20250331093827101](https://note-1259190304.cos.ap-chengdu.myqcloud.com/noteimage-20250331093827101.png) #### mat ![image-20250331093903437](https://note-1259190304.cos.ap-chengdu.myqcloud.com/noteimage-20250331093903437.png) ![image-20250331093916728](https://note-1259190304.cos.ap-chengdu.myqcloud.com/noteimage-20250331093916728.png) ![image-20250331093928007](https://note-1259190304.cos.ap-chengdu.myqcloud.com/noteimage-20250331093928007.png) ![image-20250331093938358](https://note-1259190304.cos.ap-chengdu.myqcloud.com/noteimage-20250331093938358.png) ![image-20250331093950692](https://note-1259190304.cos.ap-chengdu.myqcloud.com/noteimage-20250331093950692.png) 找出最终的引用对象 ![image-20250331094010957](https://note-1259190304.cos.ap-chengdu.myqcloud.com/noteimage-20250331094010957.png) #### GCeasy [Universal JVM GC analyzer - Java Garbage collection log analysis made easy](https://gceasy.io/)