ANR：Application Not Responding

使用Android手机有时候会遇到系统弹框“应用程序无响应”，这是因为APP在前台或者后台主线程中执行的时间太长，没有响应用户的操作。

1、ANR条件

系统ActivityManager和WindowManager会监控应用，如下三种条件下会产生ANR：

①Activity：前台在5s内无法响应输入事件(触摸、按键)；定义在：ActivityTaskManagerService

// How long we wait until we timeout on key dispatching.
    public static final int KEY_DISPATCHING_TIMEOUT_MS = 5 * 1000;
    
    // How long we wait until we timeout on key dispatching during instrumentation.
    static final int INSTRUMENTATION_KEY_DISPATCHING_TIMEOUT_MS = 60 * 1000;
    
    // How long we permit background activity starts after an activity in the process started or finished.
    static final long ACTIVITY_BG_START_GRACE_PERIOD_MS = 10 * 1000;

②BroadcastReceiver：前台广播10s，后台广播60s无法响应；定义在：ActivityManagerService

// How long we allow a receiver to run before giving up on it.
    static final int BROADCAST_FG_TIMEOUT = 10*1000;
    
    static final int BROADCAST_BG_TIMEOUT = 60*1000;

③Service：前台服务20s，后台服务200s未响应；定义在：ActiveServices

// How long we wait for a service to finish executing.
    static final int SERVICE_TIMEOUT = 20*1000;
    
    // How long we wait for a service to finish executing.
    static final int SERVICE_BACKGROUND_TIMEOUT = SERVICE_TIMEOUT * 10;
    
    // How long the startForegroundService() grace period is to get around to
    // calling startForeground() before we ANR + stop it.
    static final int SERVICE_START_FOREGROUND_TIMEOUT = 10*1000;

2、ANR分析

当应用出现ANR，这个时候就该好好通过trance分析分析到底应用程序主线程哪里进行了耗时操作，需要移到子线程中处理。打开开发者选项中的ANR开关，直观的看到系统提示ANR弹框。

2.1、示例

想造一个ANR，很简单，在前台主线程Sleep超过5s即可。

@Override
    protected void onCreate(Bundle savedInstanceState) {
        ...
        try {
            Thread.sleep(500000);
        } catch (Exception e) {
            Log.d(TAG, e.toString());
        }
    }