6
下面的簡單的代碼重新java.lang.ref.WeakReference對象的生長在堆內的對象：內存泄漏JDK類
[email protected]:~> jmap -d64 -histo:live 29201|grep WeakReference
8: 22493 1079664 java.lang.ref.WeakReference
31: 1 32144 [Ljava.lang.ref.WeakReference;
106: 17 952
com.sun.jmx.mbeanserver.WeakIdentityHashMap$IdentityWeakReference
[email protected]:~> jmap -d64 -histo:live 29201|grep WeakReference
8: 23191 1113168 java.lang.ref.WeakReference
31: 1 32144 [Ljava.lang.ref.WeakReference;
103: 17 952
com.sun.jmx.mbeanserver.WeakIdentityHashMap$IdentityWeakReference
[email protected]:~> jmap -d64 -histo:live 29201|grep WeakReference
8: 23804 1142592 java.lang.ref.WeakReference
31: 1 32144 [Ljava.lang.ref.WeakReference;
103: 17 952 com.sun.jmx.mbeanserver.WeakIdentityHashMap$IdentityWeakReference
請注意，jmap命令強制FullGC。
JVM settings:
export JVM_OPT="\
-d64 \
-Xms200m -Xmx200m \
-XX:MaxNewSize=64m \
-XX:NewSize=64m \
-XX:+UseParNewGC \
-XX:+UseConcMarkSweepGC \
-XX:MaxTenuringThreshold=10 \
-XX:SurvivorRatio=2 \
-XX:CMSInitiatingOccupancyFraction=60 \
-XX:+UseCMSInitiatingOccupancyOnly \
-XX:+CMSParallelRemarkEnabled \
-XX:+DisableExplicitGC \
-XX:+CMSClassUnloadingEnabled \
-XX:+PrintGCTimeStamps \
-XX:+PrintGCDetails \
-XX:+PrintTenuringDistribution \
-XX:+PrintGCApplicationConcurrentTime \
-XX:+PrintGCApplicationStoppedTime \
-XX:+PrintGCApplicationStoppedTime \
-XX:+PrintClassHistogram \
-XX:+ParallelRefProcEnabled \
-XX:SoftRefLRUPolicyMSPerMB=1 \
-verbose:gc \
-Xloggc:$GCLOGFILE"
java version "1.6.0_18"
Java(TM) SE Runtime Environment (build 1.6.0_18-b07)
Java HotSpot(TM) Server VM (build 16.0-b13, mixed mode)
Solaris 10/Sun Fire(TM) T1000