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Android NDK 内存泄露检测

前言

最近写C++代码,老是担心代码存在内存泄露,胆战心惊的,Andorid中Java层代码内存泄露可以借助leakcanary进行检测;找了一番,找到了PC上C++上的内存泄露检测库LeakTracer,于是再找了下,找到了Android上的移植版。

首先建立一个项目,在根目录下建立thirdparty目录,进入该目录,clone相关库代码

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git clone git@github.com:lizhangqu/LeakTracer.git

在项目src/main/cpp下建立CMakeLists.txt,内容如下

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project(Test)
cmake_minimum_required (VERSION 3.6)

include_directories(
${PROJECT_SOURCE_DIR}/include/
${PROJECT_SOURCE_DIR}/../../../../thirdparty/LeakTracer/libleaktracer/include/
)


set(LEAKTRACER_SOURCES
${PROJECT_SOURCE_DIR}/../../../../thirdparty/LeakTracer/libleaktracer/src/AllocationHandlers.cpp
#${PROJECT_SOURCE_DIR}/../../../../thirdparty/LeakTracer/libleaktracer/src/LeakTracerC.c
#检测c代码时打开此注释,否则不要打开
${PROJECT_SOURCE_DIR}/../../../../thirdparty/LeakTracer/libleaktracer/src/MemoryTrace.cpp
)

add_library(leaktracer STATIC ${LEAKTRACER_SOURCES})

set(TEST_FILES
${CMAKE_SOURCE_DIR}/native.cpp
)
add_library(
test-jni
SHARED
${TEST_FILES})

target_link_libraries(
test-jni
leaktracer
log
)

建立src/main/cpp/include/native.h和src/main/cpp/native.cpp文件

native.h

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//
// Created by 李樟取 on 2017/6/4.
//

#ifndef TEST_H
#define TEST_H

#include "jni.h"

#ifndef NELEM
# define NELEM(x) ((int) (sizeof(x) / sizeof((x)[0])))
#endif


#ifndef CLASSNAME
#define CLASSNAME "io/github/lizhangqu/test/Test"
#endif



#ifdef ANDROID

#include <android/log.h>

#define TAG "Test"

#define ALOGE(fmt, ...) __android_log_print(ANDROID_LOG_ERROR, TAG, fmt, ##__VA_ARGS__)
#define ALOGI(fmt, ...) __android_log_print(ANDROID_LOG_INFO, TAG, fmt, ##__VA_ARGS__)
#define ALOGD(fmt, ...) __android_log_print(ANDROID_LOG_DEBUG, TAG, fmt, ##__VA_ARGS__)
#define ALOGW(fmt, ...) __android_log_print(ANDROID_LOG_WARN, TAG, fmt, ##__VA_ARGS__)
#else
#define ALOGE printf
#define ALOGI printf
#define ALOGD printf
#define ALOGW printf
#endif

#endif //TEST_H

native.cpp

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#include "native.h"
#include "MemoryTrace.hpp"
#include <fstream>

void test(JNIEnv *env, jobject thiz) {

}

static const JNINativeMethod sMethods[] = {
{
const_cast<char *>("test"),
const_cast<char *>("()V"),
reinterpret_cast<void *>(test)
},

};

int registerNativeMethods(JNIEnv *env, const char *className, const JNINativeMethod *methods,
const int numMethods) {
jclass clazz = env->FindClass(className);
if (!clazz) {
ALOGE("Native registration unable to find class '%s'\n", className);
return JNI_FALSE;
}
if (env->RegisterNatives(clazz, methods, numMethods) != 0) {
ALOGE("RegisterNatives failed for '%s'\n", className);
env->DeleteLocalRef(clazz);
return JNI_FALSE;
}
env->DeleteLocalRef(clazz);
return JNI_TRUE;
}

jint JNI_OnLoad(JavaVM *vm, void *reserved) {
JNIEnv *env;
if (vm->GetEnv(reinterpret_cast<void **>(&env), JNI_VERSION_1_6) != JNI_OK) {
return -1;
}
registerNativeMethods(env, CLASSNAME, sMethods, NELEM(sMethods));
return JNI_VERSION_1_6;
}

编写test函数,简单进行内测泄露检测

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class MemoryTest {

};

void test(JNIEnv *env, jobject thiz) {
leaktracer::MemoryTrace::GetInstance().startMonitoringAllThreads();
MemoryTest *memoryTest = new MemoryTest;
leaktracer::MemoryTrace::GetInstance().stopAllMonitoring();

std::ofstream out;
out.open("/sdcard/leaks.out", std::ios_base::out);
if (out.is_open()) {
leaktracer::MemoryTrace::GetInstance().writeLeaks(out);
} else {
ALOGE("Failed to write to \"leaks.out\"\n");
}
}

运行程序后调用test函数,将/sdcard/leaks.out pull到项目根目录

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adb pull /sdcard/leaks.out

其内容类似如下内容

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# LeakTracer report diff_utc_mono=1496511718.682943
leak, time=135120.534718, stack=0x36fd6 0x35a90 0x359a4 0x32fea 0xc952d3d0, size=1, data=�

借助thirdparty/LeakTracer/helper/leak-analyze-addr2line工具还原内测泄露堆栈。

进入项目根目录,执行leak-analyze-addr2line

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./thirdparty/LeakTracer/helpers/leak-analyze-addr2line ./library/build/intermediates/cmake/debug/obj/armeabi/libtest-jni.so ./leaks.out

在mac上,会出现一个错误,原因是leak-analyze-addr2line中用到了addr2line工具,而mac上如果没有此工具,就会报错,错误如下:

error.png

解决方法很简单,将ndk目录中的arm-linux-androideabi-addr2line拷到./thirdparty/LeakTracer/helpers/下,并重命名为addr2line,然后将./thirdparty/LeakTracer/helpers/加到环境变量中,如下代码

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cp $ANDROID_NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/bin/arm-linux-androideabi-addr2line ./thirdparty/LeakTracer/helpers/addr2line
export PATH=$PATH:`pwd`/thirdparty/LeakTracer/helpers

$ANDROID_NDK_HOME表示ndk的根目录。

之后再次调用命令

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./thirdparty/LeakTracer/helpers/leak-analyze-addr2line ./library/build/intermediates/cmake/debug/obj/armeabi/libtest-jni.so ./leaks.out

这时候输出如下

out_leak.png

native.cpp:15行出现泄露,找到15行对应的代码,即如下代码出现泄露

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MemoryTest *memoryTest = new MemoryTest;

加入delete代码,再跑一次

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MemoryTest *memoryTest = new MemoryTest;
delete memoryTest;

输出如下

out_no_leak.png

发现之前的泄露不见了

最后,值得注意的是,要想使用LeakTracer需要保留so足够多的debug信息,否则可能不能正常检测。

项目Demo地址见NDKMemoryLeakSample

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