ParNew Collector - Tenuring Age Distribution

Java GC Tutorials - Herong's Tutorial Examples

∟Concurrent Mark-Sweep (CMS) Collector - "+XX:+UseConcMarkSweepGC"

∟ParNew Collector - Tenuring Age Distribution

This section demonstrates that the ParNew Collector uses Tenuring Age Distribution to perform Young generation GC.

Does the ParNew collector use Tenuring Age Distribution? Let's use our second test program, GarbageCollection2.java to find out:

herong> java -XX:+UseConcMarkSweepGC \
   -Xms1200m -Xmx1200m -XX:NewRatio=1 -XX:SurvivorRatio=1 \
   -Xlog:gc,gc+heap=debug,gc+age=trace \
   GarbageCollection2 > output.txt

herong> more output.txt
[info ][gc     ] Using Concurrent Mark Sweep
Step/TotalMemory/FreeMemory/UsedMemory:
1   1048576000   1040187352   8388648

...
193   1048576000   839906280   208669720
[gc,age ] GC(0) Desired survivor size 104857600 bytes,
                new threshold 15 (max threshold 15)
[gc,age ] GC(0) Age table with threshold 15 (max threshold 15)
[gc,age ] GC(0) - age   1:   33258632 bytes,   33258632 total

[gc,heap] GC(0) ParNew: 203779K->32501K(409600K)
[gc,heap] GC(0) CMS: 0K->0K(614400K)
[gc] GC(0) Pause Young (Allocation Failure) 199M->31M(1000M) 22.755ms

...
390   1048576000   805660552   242915448
[gc,age ] GC(1) Desired survivor size 104857600 bytes,
                new threshold 15 (max threshold 15)
[gc,age ] GC(1) Age table with threshold 15 (max threshold 15)
[gc,age ] GC(1) - age   1:   32506352 bytes,   32506352 total
[gc,age ] GC(1) - age   2:     752000 bytes,   33258352 total

[gc,heap] GC(1) ParNew: 237222K->32612K(409600K)
[gc,heap] GC(1) CMS: 0K->0K(614400K)
[gc] GC(1) Pause Young (Allocation Failure) 231M->31M(1000M) 16.683ms

...
2178   1048576000   805243072   243332928
[gc,age ] GC(10) Desired survivor size 104857600 bytes,
                 new threshold 15 (max threshold 15)
[gc,age ] GC(10) Age table with threshold 15 (max threshold 15)
[gc,age ] GC(10) - age   1:   32506352 bytes,   32506352 total
[gc,age ] GC(10) - age   2:        120 bytes,   32506472 total
[gc,age ] GC(10) - age   6:        648 bytes,   32507120 total
[gc,age ] GC(10) - age   8:        864 bytes,   32507984 total
[gc,age ] GC(10) - age   9:        192 bytes,   32508176 total
[gc,age ] GC(10) - age  11:     751968 bytes,   33260144 total

[gc,heap] GC(10) ParNew: 237629K->32940K(409600K)
[gc,heap] GC(10) CMS: 0K->0K(614400K)
[gc] GC(10) Pause Young (Allocation Failure) 232M->32M(1000M) 7.123ms