Minor GC 中 MaxTenuringThreshold 和 TargetSurvivorRatio 引數說明
阿新 • • 發佈：2019-02-03
以-Xms20M -Xmx20M -Xmn10M -XX:SurvivorRatio=1 -XX:+UseSerialGC -XX:MaxTenuringThreshold=3 -XX:+PrintTenuringDistribution -XX:+PrintGCDetails
執行上述程式碼。
[GC [DefNew
Desired survivor size 1736704 bytes, new threshold 3 (max 3)
- age 1: 363408 bytes, 363408 total
: 2529K->354K(6848K), 0.0017645 secs] 2529K->354K(17088K), 0.0018275 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
[GC [DefNew
Desired survivor size 1736704 bytes, new threshold 3 (max 3)
- age 1: 314616 bytes, 314616 total
- age 2: 363176 bytes, 677792 total
: 2748K->661K(6848K), 0.0009114 secs] 2748K->661K(17088K), 0.0009399 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
[GC [DefNew
Desired survivor size 1736704 bytes, new threshold 3 (max 3)
- age 1: 314616 bytes, 314616 total
- age 2: 314600 bytes, 629216 total
- age 3: 363176 bytes, 992392 total
: 3042K->969K(6848K), 0.0010587 secs] 3042K->969K(17088K), 0.0010872 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
[GC [DefNew
Desired survivor size 1736704 bytes, new threshold 3 (max 3)
- age 1: 314616 bytes, 314616 total
- age 2: 314600 bytes, 629216 total
- age 3: 314600 bytes, 943816 total
: 3341K->921K(6848K), 0.0012151 secs] 3341K->1276K(17088K), 0.0012443 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
ok
Heap
def new generation total 6848K, used 3049K [0x32310000, 0x32d10000, 0x32d10000)
eden space 3456K, 61% used [0x32310000, 0x32524128, 0x32670000)
from space 3392K, 27% used [0x32670000, 0x327566c8, 0x329c0000)
to space 3392K, 0% used [0x329c0000, 0x329c0000, 0x32d10000)
tenured generation total 10240K, used 354K [0x32d10000, 0x33710000, 0x33710000)
the space 10240K, 3% used [0x32d10000, 0x32d68aa8, 0x32d68c00, 0x33710000)
compacting perm gen total 12288K, used 369K [0x33710000, 0x34310000, 0x37710000)
the space 12288K, 3% used [0x33710000, 0x3376c430, 0x3376c600, 0x34310000)
ro space 10240K, 51% used [0x37710000, 0x37c3b700, 0x37c3b800, 0x38110000)
rw space 12288K, 54% used [0x38110000, 0x387a76c0, 0x387a7800, 0x38d10000)
參考：
http://cr.openjdk.java.net/~andrew/jdk6-hs14-merge/webrev.01/hotspot/src/share /vm/gc_implementation/shared/ageTable.cpp.frames.html
http://blog.bluedavy.com/?p=70
http://java.sun.com/performance/reference/whitepapers/tuning.html
http://java.sun.com/docs/hotspot/gc1.4.2/faq.html
http://www.javaworld.com/javaworld/jw-01-2002/jw-0111-hotspotgc.html
執行上述程式碼。
[GC [DefNew
Desired survivor size 1736704 bytes, new threshold 3 (max 3)
- age 1: 363408 bytes, 363408 total
: 2529K->354K(6848K), 0.0017645 secs] 2529K->354K(17088K), 0.0018275 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
[GC [DefNew
Desired survivor size 1736704 bytes, new threshold 3 (max 3)
- age 1: 314616 bytes, 314616 total
- age 2: 363176 bytes, 677792 total
: 2748K->661K(6848K), 0.0009114 secs] 2748K->661K(17088K), 0.0009399 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
[GC [DefNew
Desired survivor size 1736704 bytes, new threshold 3 (max 3)
- age 1: 314616 bytes, 314616 total
- age 2: 314600 bytes, 629216 total
- age 3: 363176 bytes, 992392 total
: 3042K->969K(6848K), 0.0010587 secs] 3042K->969K(17088K), 0.0010872 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
[GC [DefNew
Desired survivor size 1736704 bytes, new threshold 3 (max 3)
- age 1: 314616 bytes, 314616 total
- age 2: 314600 bytes, 629216 total
- age 3: 314600 bytes, 943816 total
: 3341K->921K(6848K), 0.0012151 secs] 3341K->1276K(17088K), 0.0012443 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
ok
Heap
def new generation total 6848K, used 3049K [0x32310000, 0x32d10000, 0x32d10000)
eden space 3456K, 61% used [0x32310000, 0x32524128, 0x32670000)
from space 3392K, 27% used [0x32670000, 0x327566c8, 0x329c0000)
to space 3392K, 0% used [0x329c0000, 0x329c0000, 0x32d10000)
tenured generation total 10240K, used 354K [0x32d10000, 0x33710000, 0x33710000)
the space 10240K, 3% used [0x32d10000, 0x32d68aa8, 0x32d68c00, 0x33710000)
compacting perm gen total 12288K, used 369K [0x33710000, 0x34310000, 0x37710000)
the space 12288K, 3% used [0x33710000, 0x3376c430, 0x3376c600, 0x34310000)
ro space 10240K, 51% used [0x37710000, 0x37c3b700, 0x37c3b800, 0x38110000)
rw space 12288K, 54% used [0x38110000, 0x387a76c0, 0x387a7800, 0x38d10000)
參考：
http://cr.openjdk.java.net/~andrew/jdk6-hs14-merge/webrev.01/hotspot/src/share /vm/gc_implementation/shared/ageTable.cpp.frames.html
http://blog.bluedavy.com/?p=70
http://java.sun.com/performance/reference/whitepapers/tuning.html
http://java.sun.com/docs/hotspot/gc1.4.2/faq.html
http://www.javaworld.com/javaworld/jw-01-2002/jw-0111-hotspotgc.html