java.lang.OutOfMemoryError: PermGen przestrzeń: Java odbicie

Question

używam java odbicie w kodzie tak:

Method method = LogFactory.class.getDeclaredMethod("getContextClassLoader"); 
method.setAccessible(true); 
ClassLoader classLoader = (ClassLoader)method.invoke(null); 
LogFactory.release(classLoader); 

używam jprofiler można zobaczyć wiele klasę tak sun.reflect.GeneratedMethodAccessor11

klasy te są zwiększane za zadzwoń pod numer

sun.reflect.BootstrapConstructorAccessorImpl 
sun.reflect.NativeConstructorAccessorImpl 
sun.reflect.DelegatingConstructorAccessorImpl 
sun.reflect.DelegatingClassLoader 

Myślę, że to dlatego wzrost powierzchni PermGen, jak wyczyścić te klasy?

Answer 1

Istnieje ładny artykuł omawiający temat potential native memory use in reflection delegating classloaders.

When using Java reflection, the JVM has two methods of accessing the information on the class being reflected. It can use a JNI accessor, or a Java bytecode accessor. If it uses a Java bytecode accessor, then it needs to have its own Java class and classloader (sun/reflect/GeneratedMethodAccessor class and sun/reflect/DelegatingClassLoader). Theses classes and classloaders use native memory. The accessor bytecode can also get JIT compiled, which will increase the native memory use even more. If Java reflection is used frequently, this can add up to a significant amount of native memory use. The JVM will use the JNI accessor first, then after some number of accesses on the same class, will change to use the Java bytecode accessor. This is called inflation, when the JVM changes from the JNI accessor to the bytecode accessor. Fortunately, we can control this with a Java property. The sun.reflect.inflationThreshold property tells the JVM what number of times to use the JNI accessor. If it is set to 0, then the JNI accessors are always used. Since the bytecode accessors use more native memory than the JNI ones, if we are seeing a lot of Java reflection, we will want to use the JNI accessors. To do this, we just need to set the inflationThreshold property to zero.

Set sun.reflect.inflationThreshold na 0 przez -Dsun.reflect.inflationThreshold=0 zrobi sztuczki dla ciebie.

Answer 2

Jeśli jesteś na Oracle JVM wtedy trzeba tylko ustawić:

sun.reflect.inflationThreshold=2147483647 

Jeśli jesteś na IBM JVM, wtedy trzeba ustawić:

-Dsun.reflect.inflationThreshold=0 

Należy pamiętać, że obie maszyny JVM różnią się sposobem interpretacji.

referencyjny po więcej szczegółów:

inflation_system_properties

native memory use