The default JVM 1.8 configuration does not properly configure Eden/Survivor spaces.

While the JVM default is SurvivorRatio=8 and it says so, the actual sizes of
Eden and Survivor areas are the same (which mean that SurvivorRatio=1) .

$ ./jmap -heap 25879
Attaching to process ID 25879, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.151-b12

using thread-local object allocation.
Parallel GC with 8 thread(s)

Heap Configuration:
   MinHeapFreeRatio = 0
   MaxHeapFreeRatio = 100
   MaxHeapSize = 12884901888 (12288.0MB)
   NewSize = 536870912 (512.0MB)
   MaxNewSize = 4294967296 (4096.0MB)
   OldSize = 1073741824 (1024.0MB)
   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 = 1390411776 (1326.0MB)
   used = 1390411776 (1326.0MB)
   free = 0 (0.0MB)
   100.0% used
From Space:
   capacity = 1278738432 (1219.5MB)
   used = 0 (0.0MB)
   free = 1278738432 (1219.5MB)
   0.0% used
To Space:
   capacity = 1431306240 (1365.0MB)
   used = 0 (0.0MB)
   free = 1431306240 (1365.0MB)
   0.0% used
PS Old Generation
   capacity = 8589934592 (8192.0MB)
   used = 8499819848 (8106.059883117676MB)
   free = 90114744 (85.94011688232422MB)
   98.95092630758882% used

If we explicitly add -XX:SurvivorRatio=8, it restores what it should be.

$ ./jmap -heap 7764
Attaching to process ID 7764, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.151-b12

using thread-local object allocation.
Parallel GC with 8 thread(s)

Heap Configuration:
   MinHeapFreeRatio = 0
   MaxHeapFreeRatio = 100
   MaxHeapSize = 12884901888 (12288.0MB)
   NewSize = 536870912 (512.0MB)
   MaxNewSize = 4294967296 (4096.0MB)
   OldSize = 1073741824 (1024.0MB)
   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 = 3666345984 (3496.5MB)
   used = 2636838920 (2514.6855545043945MB)
   free = 1029507064 (981.8144454956055MB)
   71.92007877890447% used
From Space:
   capacity = 157810688 (150.5MB)
   used = 114371680 (109.07333374023438MB)
   free = 43439008 (41.426666259765625MB)
   72.47397590713247% used
To Space:
   capacity = 159383552 (152.0MB)
   used = 0 (0.0MB)
   free = 159383552 (152.0MB)
   0.0% used
PS Old Generation
   capacity = 8589934592 (8192.0MB)
   used = 6882442576 (6563.60871887207MB)
   free = 1707492016 (1628.3912811279297MB)
   80.12217674404383% used