Java eden space is not 8 times larger than s0 space - garbage-collection

Question

according to oracle's doc default parameter values for SurvivorRatio is 8, that means each survivor space will be one-eighth the size of eden space.
but in my application it don't work
$ jmap -heap 48865
Attaching to process ID 48865, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.45-b02
using thread-local object allocation.
Parallel GC with 8 thread(s)
Heap Configuration:
MinHeapFreeRatio = 0
MaxHeapFreeRatio = 100
MaxHeapSize = 4294967296 (4096.0MB)
NewSize = 89128960 (85.0MB)
MaxNewSize = 1431306240 (1365.0MB)
OldSize = 179306496 (171.0MB)
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 = 67108864 (64.0MB)
used = 64519920 (61.53099060058594MB)
free = 2588944 (2.4690093994140625MB)
96.14217281341553% used
From Space:
capacity = 11010048 (10.5MB)
used = 0 (0.0MB)
free = 11010048 (10.5MB)
0.0% used
To Space:
capacity = 11010048 (10.5MB)
used = 0 (0.0MB)
free = 11010048 (10.5MB)
0.0% used
PS Old Generation
capacity = 179306496 (171.0MB)
used = 0 (0.0MB)
free = 179306496 (171.0MB)
0.0% used
7552 interned Strings occupying 605288 bytes.
but in VisualVM eden space is 1.332G and S0 is 455M, eden is only 3 times larger than S0 not the 8

Answer 1

You have neither disabled -XX:-UseAdaptiveSizePolicy, nor set -Xms equal to -Xmx, so JVM is free to resize heap generations (and survivor spaces) in runtime. In this case the estimated maximum Survior size is
MaxSurvivor = NewGen / MinSurvivorRatio
where -XX:MinSurvivorRatio=3 by default. Note: this is an estimated maximum, not the actual size.
See also this answer.