ANR概念
Android ANR全稱是Application No Responding,即應用無響應。如果主線程即UI線程在規定時間沒有處理完相應工作便會發生ANR,而具體來說便是以下四類事件
KeyDispatchTimeout:輸入和觸摸事件在5s內未得到響應
BroadcastTimeout:BroadcastReceiver廣播的onReceiver方法在規定時間(前臺10s,後臺60s)未處理完
ServiceTimeout:Service服務在規定時間(前臺20s,後臺200s)未成功啓動
ProcessContentProviderPublishTimeOutLocked:ContentProvider的publish在10s內未處理完
這裏貼一下這些時間的源碼定義
// How long we wait until we timeout on key dispatching.
static final int KEY_DISPATCHING_TIMEOUT = 5*1000;
// How long we allow a receiver to run before giving up on it.
static final int BROADCAST_FG_TIMEOUT = 10*1000; // 前臺
static final int BROADCAST_BG_TIMEOUT = 60*1000; // 後臺
// How long we wait for a service to finish executing.
static final int SERVICE_TIMEOUT = 20*1000; // 前臺
// How long we wait for a service to finish executing.
static final int SERVICE_BACKGROUND_TIMEOUT = SERVICE_TIMEOUT * 10; // 後臺
// How long we wait for an attached process to publish its content providers
// before we decide it must be hung.
static final int CONTENT_PROVIDER_PUBLISH_TIMEOUT = 10*1000;
而ANR的具體觸發原理可以看這篇博客理解Android ANR的觸發原理,後續再跟着這篇博客進一步學習ANR觸發機制源碼
當ANR發生時如何定位原因呢
當ANR發生時,Android會在Loacat中打印日誌,內容包括
導致ANR的類名及所在包名,例如MainActivity,org.wolf.anrtest
發生ANR的進程名稱及ID,例如org.wolf.anrtest,8645
ANR的類型(即發生原因),例如Input dispatching time out,則屬於KeyDispatchTimeout類型
系統中活躍進程的CPU佔有率,例如1.8% 8645/org.wolf.anrtest:0.8% user+0.5% kernel/faults:8215 minor 16 major.
並且會生成/data/anr/traces.txt文件記錄更多詳細信息