以下简单代码重现java.lang.ref.WeakReference了堆中对象的增长:
public static void main(String[] args) throws Exception {
while (true) {
java.util.logging.Logger.getAnonymousLogger();
Thread.sleep(1);
}
}
以下是几秒间隔内jmap命令的输出:
user@t1007:~> 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$IdentityWeakReference
user@t1007:~> jmap -d64 -histo:live 29201|grep WeakReference
8: 23191 1113168 java.lang.ref.WeakReference
31: 1 32144 [Ljava.lang.ref.WeakReference;
103: 17 952
com.sun.jmx.mbeanserver.WeakIdentityHashMap$IdentityWeakReference
user@t1007:~> 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
请注意,jmap命令强制使用FullGC.
JVM settings:
export JVM_OPT="\
-d64 \ …