Android工具:LeakCanary—内存泄露检测神器
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一、LeakCanary简介LeakCanary是Square公司开源的一个检测内存的泄露的函数库,可以方便地和你的项目进行集成,在Debug版本中监控Activity、Fragment等的内存泄露;
LeakCanary集成到项目中之后,在检测到内存泄露时,会发送消息到系统通知栏。点击后打开名称DisplayLeakActivity的页面,并显示泄露的跟踪信息,Logcat上面也会有对应的日志输出。同时如果跟踪信息不足以定位时,DisplayLeakActivity还为开发者默认保存了最近7个dump文件到App的目录中,可以使用MAT等工具对dump文件进行进一步的分析;
二、内存泄漏简介
在了解了LeakCanary的接入方式后,我们肯定着急想见识见识LeakCanary的威力。在跟大家演示LeakCanary检测和处理构成之前,大家应该明应该对内存泄露有基本的了解和认识;
1.为什么会产生内存泄漏?
当一个对象不需要使用本该回收时,有另外一个正在使用的对象持有它的引用,从而导致它不能回收停留在堆内存中,这就产生了内存泄漏;
2.内存泄露对程序产生的影响?
内存泄漏是造成应用程序OOM的主要原因之一。android系统为每个应用程序分配有限的内存,当应用中内存泄漏较多时,就难免会导致应用所需要的内存超出系统分配限额,从而导致OOM应用Crash;
3.Android常见的内存泄露?
相信内存泄露对大家都早有耳闻,但是它不像一些Java异常情况,会立即造成程序的Crash,却有让大家比较“陌生”。下面我们就列举出日常开发中常见的内存泄露类型,让大家对内存泄露的认识不仅仅停留在“有所耳闻 ”的层面;
单例造成:由于单例静态特性使得单例的生命周期和应用的生命周期一样长,如果一个对象(如Context)已经不使用了,而单例对象还持有对象的引用造成这个对象不能正常被回收;
非静态内部类创建静态实例造成:在Acitivity内存创建一个非静态内部类单例,避免每次启动资源重新创建。但是因为非静态内部类默认持有外部类(Activity)的引用,并且使用该类创建静态实例。造成该实例和应用生命周期一样长,导致静态实例持有引用的Activity和资源不能正常回收;
Handler造成:子线程执行网络任务,使用Handler处理子线程发送消息。由于handler对象是非静态匿名内部类的对象,持有外部类(Activity)的引用。在Handler-Message中Looper线程不断轮询处理消息,当Activity退出还有未处理或者正在处理的消息时,消息队列中的消息持有handler对象引用,handler又持有Activity,导致Activity的内存和资源不能及时回收;
线程造成:匿名内部类Runnalbe和AsyncTask对象执行异步任务,对当前Activity隐式引用。当Activity销毁之前,任务还没有执行完,将导致Activity的内存和资源不能及时回收;
资源未关闭造成的内存泄露:对于使用了BroadcastReceiver,ContentObserver,File,Cursor,Stream,Bitmap等资源的使用,应该在Activity销毁时及时关闭或者注销,否则这些资源将不会被回收,造成内存泄露;
三、LeakCanary接入
下面我们还是以QProject项目进行演示如何在项目中接入LeakCanary,项目目录如下:
1.添加LeakCanary依赖
在主项目main模块的build.gradle文件中添加LeakCanary相关依赖;
/main/build.gradle文件
apply plugin: 'com.android.application'
android {
... ...
}
dependencies {
... ...
//添加leakcanary相关的依赖
//在release和test版本中,使用的是LeakCanary的no-op版本,也就是没有实际代码和操作的Wrapper版本,只包含LeakCanary和RefWatcher类的空实现,这样不会对生成的APK包体积和应用性能造成影响
debugCompile 'com.squareup.leakcanary:leakcanary-android:1.5'
releaseCompile 'com.squareup.leakcanary:leakcanary-android-no-op:1.5'
testCompile 'com.squareup.leakcanary:leakcanary-android-no-op:1.5'
... ...
compile project(':test')
}
2.初始化LeakCanary
在主项目main模块的QApplication的onCreate()方法中初始化LeakCanary;
/main/src/main/java/com/qproject/main/QApplication.java文件
public class QAplication extends Application{
@Override
public void onCreate() {
super.onCreate();
... ...
//初始化LeakCanary
if (LeakCanary.isInAnalyzerProcess(this)) {
return;
}
LeakCanary.install(this);
}
}
OK,到这里我们就完成了一个项目的LeankCanary的简单接入;
提示1:集成LeakCanary后,构建和安装apk的时候报错如下:
Error:Error converting bytecode to dex:
Cause: com.android.dex.DexException: Multiple dex files define Lcom/squareup/leakcanary/LeakCanary;
Error:Execution failed for task ':main:transformClassesWithDexForDebug'.
> com.android.build.api.transform.TransformException: com.android.ide.common.process.ProcessException: java.util.concurrent.ExecutionException: java.lang.UnsupportedOperationException
处理1:添加依赖debugCompile 'com.squareup.haha:haha:2.0.3',修改依赖的版本为1.4-beta2;
四、LeakCanary检测
通过对一些常见的内存泄露的学习,我们已经对内存泄露有所见闻了。那么下面我们通过LeakCanary工具,让大家感受下它在你的日常开发中的真实存在。我们以常见内存—单例造成的内存泄露为例进行实践;
1.单例内存泄露模拟
test/src/main/com/qproject/test/TestManager.java
public class TestManager {
//单例静态特性使得单例的生命周期和应用的生命周期一样长
private static TestManager instance;
private Context context;
/**
* 传入的Context的生命周期很重要:
* 如果传入的是Application的Context,则生命周期和单例生命周期一样长;
* 如果传入的是Activity的Context,由于该Context和Activity的生命周期一样长,当Activity退出的时候它的内存不会被回收,因为单例对象持有它的引用;
*/
private TestManager(Context context) {
this.context = context;
}
public static TestManager getInstance(Context context) {
if (instance == null) {
instance = new TestManager(context);
}
return instance;
}
}
test/src/main/com/qproject/test/leakcanary/LeakCanaryActivity.java
public class LeakCanaryActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_leakcanary);
//获取单例对象,退出Activity即可模拟出内存泄露
TestManager testManager = TestManager.getInstance(this);
}
}
2.检测消息通知
运行App到LeakCanaryActivit页面并退出,在检测到内存泄露的时候,会发送消息到系统通知栏;
3.查看检测详情
点击通知消息,打开名为DisplayLeakActivity的页面,并显示泄漏的跟踪信息;
4.查看LogCat日志
除了以上泄漏信息的显示,Logcat上面也会有对应的日志输出;
//内存泄露对象com.qproject.test.leakcanary.LeakCanaryActivity
12-25 07:50:51.710 4941-5795/com.qproject.main D/LeakCanary: * com.qproject.test.leakcanary.LeakCanaryActivity has leaked:
//static com.qproject.test.TestManager.instance的com.qproject.test.TestManager.context引用了回收的内存对象
12-25 07:50:51.710 4941-5795/com.qproject.main D/LeakCanary: * GC ROOT static com.qproject.test.TestManager.instance
12-25 07:50:51.710 4941-5795/com.qproject.main D/LeakCanary: * references com.qproject.test.TestManager.context
//内存泄露对象大小,Reference Key,Device和Android Version等信息
12-25 07:50:51.710 4941-5795/com.qproject.main D/LeakCanary: * leaks com.qproject.test.leakcanary.LeakCanaryActivity instance
12-25 07:50:51.710 4941-5795/com.qproject.main D/LeakCanary: * Retaining: 46 KB.
12-25 07:50:51.710 4941-5795/com.qproject.main D/LeakCanary: * Reference Key: 3d74d294-70dc-4447-a9a2-64e656ea86b8
12-25 07:50:51.710 4941-5795/com.qproject.main D/LeakCanary: * Device: Genymotion Android PREVIEW - Google Nexus 5X - 7.0.0 - API 24 - 1080x1920 vbox86p
12-25 07:50:51.710 4941-5795/com.qproject.main D/LeakCanary: * Android Version: 7.0 API: 24 LeakCanary: 1.5 00f37f5
12-25 07:50:51.710 4941-5795/com.qproject.main D/LeakCanary: * Durations: watch=5038ms, gc=137ms, heap dump=2390ms, analysis=27325ms
//内存泄露对象详细信息
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: * Details:
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: * Class com.qproject.test.TestManager
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | static instance = com.qproject.test.TestManager@316184816 (0x12d898f0)
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | static $classOverhead = byte[308]@316175745 (0x12d87581)
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: * Instance of com.qproject.test.TestManager
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | static instance = com.qproject.test.TestManager@316184816 (0x12d898f0)
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | static $classOverhead = byte[308]@316175745 (0x12d87581)
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | context = com.qproject.test.leakcanary.LeakCanaryActivity@315059712 (0x12c76e00)
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | shadow$_klass_ = com.qproject.test.TestManager
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | shadow$_monitor_ = 0
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: * Instance of com.qproject.test.leakcanary.LeakCanaryActivity
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | static $classOverhead = byte[2228]@316203009 (0x12d8e001)
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mDelegate = android.support.v7.app.AppCompatDelegateImplN@315842128 (0x12d35e50)
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mEatKeyUpEvent = false
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mResources = null
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mThemeId = 2131230884
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mCreated = true
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mFragments = android.support.v4.app.FragmentController@316183584 (0x12d89420)
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mHandler = android.support.v4.app.FragmentActivity$1@316163360 (0x12d84520)
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mNextCandidateRequestIndex = 0
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mOptionsMenuInvalidated = false
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mPendingFragmentActivityResults = android.support.v4.util.SparseArrayCompat@316172368 (0x12d86850)
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mReallyStopped = true
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mRequestedPermissionsFromFragment = false
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mResumed = false
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mRetaining = false
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mStopped = true
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mStartedActivityFromFragment = false
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mStartedIntentSenderFromFragment = false
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mExtraDataMap = android.support.v4.util.SimpleArrayMap@316171864 (0x12d86658)
12-25 07:50:51.711 4941-5795/com.qproject.main D/LeakCanary: | mActionBar = null
12-25 07:50:51.712 4941-5795/com.qproject.main D/LeakCanary: | mActionModeTypeStarting = 0
12-25 07:50:51.712 4941-5795/com.qproject.main D/LeakCanary: | mActivityInfo = android.content.pm.ActivityInfo@315841984 (0x12d35dc0)
12-25 07:50:51.712 4941-5795/com.qproject.main D/LeakCanary: | mActivityTransitionState = android.app.ActivityTransitionState@316207336 (0x12d8f0e8)
12-25 07:50:51.712 4941-5795/com.qproject.main D/LeakCanary: | mApplication = com.qproject.main.QAplication@314916416 (0x12c53e40)
12-25 07:50:51.712 4941-5795/com.qproject.main D/LeakCanary: | mCalled = true
12-25 07:50:51.712 4941-5795/com.qproject.main D/LeakCanary: | mChangeCanvasToTranslucent = false
12-25 07:50:51.712 4941-5795/com.qproject.main D/LeakCanary: | mChangingConfigurations = false
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mComponent = android.content.ComponentName@315998320 (0x12d5c070)
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mConfigChangeFlags = 0
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mCurrentConfig = android.content.res.Configuration@316178888 (0x12d881c8)
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mDecor = null
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mDefaultKeyMode = 0
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mDefaultKeySsb = null
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mDestroyed = true
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mDoReportFullyDrawn = false
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mEatKeyUpEvent = false
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mEmbeddedID = null
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mEnableDefaultActionBarUp = false
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mEnterTransitionListener = android.app.SharedElementCallback$1@1887062680 (0x707a4a98)
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mExitTransitionListener = android.app.SharedElementCallback$1@1887062680 (0x707a4a98)
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mFinished = true
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mFragments = android.app.FragmentController@316183536 (0x12d893f0)
12-25 07:50:51.713 4941-5795/com.qproject.main D/LeakCanary: | mHandler = android.os.Handler@316163296 (0x12d844e0)
12-25 07:50:51.714 4941-5795/com.qproject.main D/LeakCanary: | mHasCurrentPermissionsRequest = false
12-25 07:50:51.714 4941-5795/com.qproject.main D/LeakCanary: | mIdent = 20356640
12-25 07:50:51.714 4941-5795/com.qproject.main D/LeakCanary: | mInstanceTracker = android.os.StrictMode$InstanceTracker@316183552 (0x12d89400)
12-25 07:50:51.714 4941-5795/com.qproject.main D/LeakCanary: | mInstrumentation = android.app.Instrumentation@314950632 (0x12c5c3e8)
12-25 07:50:51.714 4941-5795/com.qproject.main D/LeakCanary: | mIntent = android.content.Intent@316215416 (0x12d91078)
12-25 07:50:51.714 4941-5795/com.qproject.main D/LeakCanary: | mLastNonConfigurationInstances = null
12-25 07:50:51.714 4941-5795/com.qproject.main D/LeakCanary: | mMainThread = android.app.ActivityThread@314966272 (0x12c60100)
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mManagedCursors = java.util.ArrayList@316171816 (0x12d86628)
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mManagedDialogs = null
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mMenuInflater = null
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mParent = null
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mReferrer = java.lang.String@316215864 (0x12d91238)
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mResultCode = 0
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mResultData = null
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mResumed = false
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mSearchEvent = null
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mSearchManager = null
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mStartedActivity = false
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mStopped = true
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mTaskDescription = android.app.ActivityManager$TaskDescription@316163328 (0x12d84500)
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mTemporaryPause = false
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mTitle = java.lang.String@315129824 (0x12c87fe0)
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mTitleColor = 0
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mTitleReady = true
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mToken = android.os.BinderProxy@315867328 (0x12d3c0c0)
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mTranslucentCallback = null
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mUiThread = java.lang.Thread@1959751680 (0x74cf7000)
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mVisibleBehind = false
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mVisibleFromClient = true
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mVisibleFromServer = true
12-25 07:50:51.715 4941-5795/com.qproject.main D/LeakCanary: | mVoiceInteractor = null
12-25 07:50:51.716 4941-5795/com.qproject.main D/LeakCanary: | mWindow = com.android.internal.policy.PhoneWindow@315116864 (0x12c84d40)
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | mWindowAdded = true
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | mWindowManager = android.view.WindowManagerImpl@316172152 (0x12d86778)
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | mInflater = com.android.internal.policy.PhoneLayoutInflater@316010352 (0x12d5ef70)
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | mOverrideConfiguration = null
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | mResources = android.content.res.Resources@316235992 (0x12d960d8)
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | mTheme = android.content.res.Resources$Theme@316183728 (0x12d894b0)
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | mThemeResource = 2131230884
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | mBase = android.app.ContextImpl@316155392 (0x12d82600)
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | shadow$_klass_ = com.qproject.test.leakcanary.LeakCanaryActivity
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | shadow$_monitor_ = 1316364430
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: * Excluded Refs:
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | Field: android.view.Choreographer$FrameDisplayEventReceiver.mMessageQueue (always)
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | Thread:FinalizerWatchdogDaemon (always)
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | Thread:main (always)
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | Thread:LeakCanary-Heap-Dump (always)
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | Class:java.lang.ref.WeakReference (always)
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | Class:java.lang.ref.SoftReference (always)
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | Class:java.lang.ref.PhantomReference (always)
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | Class:java.lang.ref.Finalizer (always)
12-25 07:50:51.717 4941-5795/com.qproject.main D/LeakCanary: | Class:java.lang.ref.FinalizerReference (always)
5.获取dump日志文件
如果觉得跟踪信息不足以定位时,DisplayLeakActivity还为开发者默认保存了最近7个dump文件到APP的目录中,可以使用MAT等工具对dump文件进行进一步的分析;
vbox86p:/data/data/com.qproject.main/files/leakcanary # ls
2016-12-25_07-50-51_718.hprof 2016-12-25_07-50-51_718.hprof.result
D:\\>adb pull ./data/data/com.qproject.main/files/leakcanary/2016-12-25_07-50-51_ 718.hprof
[100%] ./data/data/com.qproject.main/f...akcanary/2016-12-25_07-50-51_718.hprof
Android Studio->View->Tool Windows->Captures,打开Captures窗口,将pull获取的hprof文件剪切到Capture中文件的目录下,双击打开即可;
具体的分析过程,这里就不重点讲述,大家去查询MAT相关的资料;
五、检测其他对象
如果想监听其他的对象(例如Fragment ),可以通过RefWatcher的实例来实现;
六、LeakCanary原理
1.RefWatcher.watch()函数会为被监控的对象创建一个KeyedWeakReference弱引用对象,是WeakReference对的子类,增加了键值对信息,后面会根据指定的键key找到弱引用对象;
2.在后台线程AndroidWatchExecutor中,检查KeyedWeakReference弱引用是否已经被清楚。如果还存在,则触发一次垃圾回收之后。垃圾回收之后,如果弱引用对象依然存在,说明发生了内存泄露;
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