JNI内存泄露JNI ERROR (app bug): local reference table overflow (max=512)

Posted 2020-09-26

原因是没即时释放对象，原本的代码是这样

static jobject getMaps(JNIEnv *env,jclass obj)
{
	jclass stringbuilder_class = (*env)->FindClass(env,"java/lang/StringBuilder");
	
	jmethodID init_stringbuilder_Method = (*env)->GetMethodID(env,stringbuilder_class,"<init>","()V");
	
	jobject stringbuilder_obj=(*env)->NewObject(env,stringbuilder_class,init_stringbuilder_Method);
	
	
	
	jmethodID append_Method = (*env)->GetMethodID(env,stringbuilder_class,"append","(Ljava/lang/Object;)Ljava/lang/StringBuilder;");
	

	FILE * fileP;
	char item[200]="ii";
	
	fileP = fopen( "/proc/self/maps","r");
	
	if(!fileP)
		return stringbuilder_obj;
	while(fgets(item,sizeof(item),fileP)!=NULL)
	{
	
		jstring str = (*env)->NewStringUTF(env,item);
		
		(*env)->CallObjectMethod(env,stringbuilder_obj,append_Method,str);
		
		(*env)->ReleaseStringUTFChars(env,str,item);
		(*env)->DeleteLocalRef(env,str);

	}
	return stringbuilder_obj;
	
}

 

直接看去好像没什么问题，但是每调用一次    (*env)->CallObjectMethod(env,stringbuilder_obj,append_Method,str)

 

;都会产生个对象，我一开始以为这样没事，改成这样程序就不崩了

 

static jobject getMaps(JNIEnv *env,jclass obj)
{
	jclass stringbuilder_class = (*env)->FindClass(env,"java/lang/StringBuilder");
	
	jmethodID init_stringbuilder_Method = (*env)->GetMethodID(env,stringbuilder_class,"<init>","()V");
	
	jobject stringbuilder_obj=(*env)->NewObject(env,stringbuilder_class,init_stringbuilder_Method);
	
	
	
	jmethodID append_Method = (*env)->GetMethodID(env,stringbuilder_class,"append","(Ljava/lang/Object;)Ljava/lang/StringBuilder;");
	

	FILE * fileP;
	char item[200]="ii";
	
	fileP = fopen( "/proc/self/maps","r");
	
	if(!fileP)
		return stringbuilder_obj;
	while(fgets(item,sizeof(item),fileP)!=NULL)
	{
	
		jstring str = (*env)->NewStringUTF(env,item);
		//加个temp用来释放
		jobject temp=(*env)->CallObjectMethod(env,stringbuilder_obj,append_Method,str);
		
		(*env)->ReleaseStringUTFChars(env,str,item);
		(*env)->DeleteLocalRef(env,str);
		(*env)->DeleteLocalRef(env,temp);
	}
	return stringbuilder_obj;
	
}