JVM Performance tuning (out of memory memories overflow/leak out)

JVM Basics:

JVM Tuning Tools:

1.jmap

Jmap Common parameters

Command: Jmap-heap PID >> D:\heap.log

Explain:

Using Thread-local object allocation.---Using native threads to assign the Mark Sweep Compact GC---tag MSC GC (MSC is a CMS GC algorithm Full GC algorithm) Heap Configuration: # #堆配置情况 minheapfreeratio = # #最小堆使用比   Example (after GC, if the free heap memory is found to occupy 40% of the entire heap, the upper limit is increased) Maxheapfreeratio = # #最大堆可用比例 (after GC, if the free heap memory is found to occupy 70% of the entire heap, the upper limit value is shrunk) Maxheapsize = 1073741824 (1024.0MB) # #最大堆空间大小 1G NewSize = 1048576 (1.0MB) # #新生代分配大小 1M M Axnewsize = 4294901760 (4095.9375MB) # #最大可新生代分配大小 4G oldsize = 4194304 (4.0MB) # #老生代大小 4M N                         Ewratio = 2 # #新生代比例 (the heap memory footprint of the Cenozoic and older generations, for example: 2 means that the Cenozoic represents 1/2 of the old generation, accounting for the entire heap of memory 1/3) Survivorratio = 8 # #新生代与suvivor的比例 (The occupancy ratio of Eden and survivor.  For example: 8 means a survivor area consumes 1/8 of Eden memory, or 1/10 of the Cenozoic memory) PermSize = 268435456 (256.0MB) # #perm区大小 MaxPermSize =                                  268435456 (256.0MB) # #最大可分配perm区大小Heap Usage:   # #堆使用情况New Generation (eden + 1 Survivor space): # #新生代 (Eden District + survior) capacity = 322109440 (307.1875MB)    # #新生代容量307M used = 226237024 (215.75643920898438MB) # #已经使用大小215M free = 95872416 (91.43106079101562MB)    # #剩余容量91M 70.23607380150051% used # #使用比例70%eden Space: # #伊甸区   Capacity = 286326784 (273.0625MB) # #伊甸区容量 273M used = 206511520 (196.94473266601562MB) # #已经使用大小196M Free = 79815264 (76.11776733398438MB) # #剩余容量76M 72.12441571655413% used # #使用比例72%from Space     : # #survior1区 capacity = 35782656 (34.125MB) # #survior1容量 34M used = 19725504 (18.81170654296875MB) # #已经使用大小 18M free = 16057152 (15.31329345703125MB) # #剩余容量 15M 55.1258799     79395606% used # #使用比例55%to space:# #survior2区 capacity = 35782656 (34.125MB) # #survior2容量 34M used = 0 (0.0MB) # #已经使用大小 0M free = 35782656 (34.125MB) # #剩余容量 34M 0.0% used# #使用比例0%tenured generation:# #老生代使用情况 capacity = 715849728 (682.6 875MB) # #老生代容量 682M used = 112533120 (107.3199462890625MB) # #已经使用大小 107M free = 603316608 (575.3675537109375MB) #   #剩余容量 575M 15.72021551428179% used# #使用比例15%perm generation:# #perm区使用情况 capacity = 268435456 (256.0MB) # #perm区容量 256M used = 83002880 (79.15771484375MB) # #已经使用大小 79M free = 185432576 (176.84228515625MB) # #剩余容量 176M 30.920982360839 844% used# #使用比例30%

　　

JVM Performance tuning (out of memory memories overflow/leak out)