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使用 -heap 查看heap空间概要
1 jmap -heap 41565 > ~/jmap.txt
Console Output
1 Attaching to process ID 41565, please wait... 2 Debugger attached successfully. 3 Server compiler detected. 4 JVM version is 25.131-b11 5 6 using parallel threads in the new generation. 7 using thread-local object allocation. 8 Concurrent Mark-Sweep GC 9 10 Heap Configuration: 11 MinHeapFreeRatio = 40 12 MaxHeapFreeRatio = 70 13 MaxHeapSize = 1073741824 (1024.0MB) 14 NewSize = 89456640 (85.3125MB) 15 MaxNewSize = 348913664 (332.75MB) 16 OldSize = 178978816 (170.6875MB) 17 NewRatio = 2 18 SurvivorRatio = 8 19 MetaspaceSize = 21807104 (20.796875MB) 20 CompressedClassSpaceSize = 1073741824 (1024.0MB) 21 MaxMetaspaceSize = 17592186044415 MB 22 G1HeapRegionSize = 0 (0.0MB) 23 24 Heap Usage: 25 New Generation (Eden + 1 Survivor Space): 26 capacity = 314048512 (299.5MB) 27 used = 314048496 (299.49998474121094MB) 28 free = 16 (1.52587890625E-5MB) 29 99.99999490524573% used 30 Eden Space: 31 capacity = 279183360 (266.25MB) 32 used = 279183360 (266.25MB) 33 free = 0 (0.0MB) 34 100.0% used 35 From Space: 36 capacity = 34865152 (33.25MB) 37 used = 34865136 (33.24998474121094MB) 38 free = 16 (1.52587890625E-5MB) 39 99.99995410890507% used 40 To Space: 41 capacity = 34865152 (33.25MB) 42 used = 0 (0.0MB) 43 free = 34865152 (33.25MB) 44 0.0% used 45 concurrent mark-sweep generation: 46 capacity = 724828160 (691.25MB) 47 used = 724828160 (691.25MB) 48 free = 0 (0.0MB) 49 100.0% used 50 51 38460 interned Strings occupying 4469136 bytes.
使用 -histo:live 查看内存中有哪些对象
1 jmap -histo:live 41565 > ~/jmap.txt
Reference
https://docs.oracle.com/javase/8/docs/technotes/tools/unix/jmap.html