[Android Pro] 分析 Package manager has died

reference to : http://blog.csdn.net/xxooyc/article/details/50162523

这是今天遇到的一个issue,由于Binder造成的。虽然比较简单，还是保持记录下吧。

先来开看一下Crash log:

    E/HpnsService(24810): HPNS Version is 5.0java.lang.RuntimeException: Package manager has died
    E/HpnsService(24810):   at android.app.ApplicationPackageManager.getPackageInfo(ApplicationPackageManager.java:111)
    E/HpnsService(24810):   at com.xx.xxx.util.AppUtil.checkInstalledPackageVersionCode(AppUtil.java:568)
    E/HpnsService(24810):   at com.xx.xxx.util.AppUtil.checkAppStatus(AppUtil.java:653)
    E/HpnsService(24810):   at com.xx.xxx.view.AppListView$LoadingAppThread.run(AppListView.java:723)
    E/HpnsService(24810): Caused by: android.os.TransactionTooLargeException
    E/HpnsService(24810):   at android.os.BinderProxy.transactNative(Native Method)
    E/HpnsService(24810):   at android.os.BinderProxy.transact(Binder.java:496)
    E/HpnsService(24810):   at android.content.pm.IPackageManager$Stub$Proxy.getPackageInfo(IPackageManager.java:1786)
    E/HpnsService(24810):   at android.app.ApplicationPackageManager.getPackageInfo(ApplicationPackageManager.java:106)
    E/HpnsService(24810):   ... 3 more

为什么会发生Package manager has died？

frameworks/base/core/java/Android/app/ApplicationPackageManager.java:

102    @Override
103    public PackageInfo getPackageInfo(String packageName, int flags)
104            throws NameNotFoundException {
105        try {
106            PackageInfo pi = mPM.getPackageInfo(packageName, flags, mContext.getUserId());
107            if (pi != null) {
108                return pi;
109            }
110        } catch (RemoteException e) {
111            throw new RuntimeException("Package manager has died", e);
112        }
113
114        throw new NameNotFoundException(packageName);
115    }

这是一个Binder调用，造成这个的原因是因为发生了RemoteException。

那为什么友会发生RemoteException？

其实也就是下面的这句Caused by: android.os.TransactionTooLargeException造成的。

为什么会造成TransactionTooLargeException？

frameworks/base/core/jni/android_util_Binder.cpp：

    682        case FAILED_TRANSACTION:
    683            ALOGE("!!! FAILED BINDER TRANSACTION !!!");
    684            // TransactionTooLargeException is a checked exception, only throw from certain methods.
    685            // FIXME: Transaction too large is the most common reason for FAILED_TRANSACTION
    686            //        but it is not the only one.  The Binder driver can return BR_FAILED_REPLY
    687            //        for other reasons also, such as if the transaction is malformed or
    688            //        refers to an FD that has been closed.  We should change the driver
    689            //        to enable us to distinguish these cases in the future.
    690            jniThrowException(env, canThrowRemoteException
    691                    ? "android/os/TransactionTooLargeException"
    692                            : "java/lang/RuntimeException", NULL);
    693            break;

可以看出如果Binder的使用超出了一个进程的限制就会抛出TransactionTooLargeException这个异常。

如果是其他原因造成Binder crash的话就会抛出RuntimeException。

那一个进程的Binder内存限制是多少？

frameworks/native/libs/binder/ProcessState.cpp：

44 #define BINDER_VM_SIZE ((1*1024*1024) - (4096 *2))

这便是一个进程中binder的大小，大约1M。

给Binder分配内存的代码：

    349#if !defined(HAVE_WIN32_IPC)
    350        // mmap the binder, providing a chunk of virtual address space to receive transactions.
    351        mVMStart = mmap(0, BINDER_VM_SIZE, PROT_READ, MAP_PRIVATE | MAP_NORESERVE, mDriverFD, 0);
    352        if (mVMStart == MAP_FAILED) {
    353            // *sigh*
    354            ALOGE("Using /dev/binder failed: unable to mmap transaction memory.\n");
    355            close(mDriverFD);
    356            mDriverFD = -1;
    357        }

通过上面的清理，知道了如果一个进程中使用的Binder内容超过了1M，就会crash.

而如果这时候恰巧在用getPackageManager()做事情，就会提示Package manager has died。

可以事实真的是这样的吗？

写了个demo来证明一下：

    public class MainActivity extends Activity {  

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            test();
        }  

        private void test() {
            for (int i = 0; i < 2; i++) {
            new Thread() {
                @Override
                public void run() {
                    int count = 0;
                        List<PackageInfo> list = getPackageManager()
                                .getInstalledPackages(10000);
                        for (PackageInfo info : list) {
                            if(count >=1000){
                                break;
                            }
                            try {
                                PackageInfo pi = getPackageManager()
                                        .getPackageInfo(info.packageName,
                                                PackageManager.GET_ACTIVITIES);
                                Log.e("yanchen", "yanchen threadid:"+Thread.currentThread().getId()
                                        + ",i:" + count++);
                            } catch (NameNotFoundException e) {
                            }
                    }
                }
            }.start();
        }
        }
    }

这个Demo就是同时创建两个线程来进行Binder调用.

运行打印的log:

    E/yanchen (21180): yanchen threadid:4097,i:271
    E/yanchen (21180): yanchen threadid:4097,i:272
    E/yanchen (21180): yanchen threadid:4097,i:273
    E/yanchen (21180): yanchen threadid:4097,i:274
    E/yanchen (21180): yanchen threadid:4097,i:275
    E/yanchen (21180): yanchen threadid:4097,i:276

此时也如预期发生了Crash:

    E/JavaBinder(31244): !!! FAILED BINDER TRANSACTION !!!
    E/AndroidRuntime(31244): FATAL EXCEPTION: Thread-4798
    E/AndroidRuntime(31244): Process: com.example.testdl, PID: 31244
    E/AndroidRuntime(31244): java.lang.RuntimeException: Package manager has died
    E/AndroidRuntime(31244):    at android.app.ApplicationPackageManager.getPackageInfo(ApplicationPackageManager.java:155)
    E/AndroidRuntime(31244):    at com.example.testdl.MainActivity$1.run(MainActivity.java:40)
    E/AndroidRuntime(31244): Caused by: android.os.TransactionTooLargeException
    E/AndroidRuntime(31244):    at android.os.BinderProxy.transactNative(Native Method)
    E/AndroidRuntime(31244):    at android.os.BinderProxy.transact(Binder.java:496)
    E/AndroidRuntime(31244):    at android.content.pm.IPackageManager$Stub$Proxy.getPackageInfo(IPackageManager.java:2208)
    E/AndroidRuntime(31244):    at android.app.ApplicationPackageManager.getPackageInfo(ApplicationPackageManager.java:150)
    E/AndroidRuntime(31244):    ... 1 more
    D/EnterpriseDeviceManagerService( 3021): isMana

解决方式：

其实只要避免多个线程同时来调用Binder就可以了，毕竟一个线程用了会释放，所以理论上是很难发生的。

修改后的Demo:

    synchronized(MainActivity.class){
        PackageInfo pi = getPackageManager()
                .getPackageInfo(info.packageName,
                        PackageManager.GET_ACTIVITIES);
    }

再次运行就不会Crash了。