### jmap ``` jmap -histo 17592 ##查看JVM内存对象分布情况 jmap -dump:format=b,file=heapdump.phrof pid ### 生成堆转储快照dump文件 ``` ### jmap -heap pid 查看目前堆情况 ``` [xixicat@cloud01 ~]$ jmap -heap 22869 Attaching to process ID 22869, please wait... Debugger attached successfully. Server compiler detected. JVM version is 23.21-b01 using thread-local object allocation. Garbage-First (G1) GC with 4 thread(s) Heap Configuration: MinHeapFreeRatio = 40 MaxHeapFreeRatio = 70 MaxHeapSize = 5368709120 (5120.0MB) NewSize = 1363144 (1.2999954223632812MB) MaxNewSize = 17592186044415 MB OldSize = 5452592 (5.1999969482421875MB) NewRatio = 2 SurvivorRatio = 8 PermSize = 20971520 (20.0MB) MaxPermSize = 268435456 (256.0MB) G1HeapRegionSize = 2097152 (2.0MB) Heap Usage: G1 Heap: regions = 2560 capacity = 5368709120 (5120.0MB) used = 3826721792 (3649.4462890625MB) free = 1541987328 (1470.5537109375MB) 71.27824783325195% used G1 Young Generation: Eden Space: regions = 1068 capacity = 2808086528 (2678.0MB) used = 2239758336 (2136.0MB) free = 568328192 (542.0MB) 79.76101568334578% used Survivor Space: regions = 29 capacity = 60817408 (58.0MB) used = 60817408 (58.0MB) free = 0 (0.0MB) 100.0% used G1 Old Generation: regions = 1000 capacity = 2499805184 (2384.0MB) used = 1524048896 (1453.4462890625MB) free = 975756288 (930.5537109375MB) 60.96670675597735% used Perm Generation: capacity = 171966464 (164.0MB) used = 170752872 (162.8426284790039MB) free = 1213592 (1.1573715209960938MB) 99.29428565792921% used 48213 interned Strings occupying 5246936 bytes. ```