Android: 怎样设置app不被系统k掉

 

android:persistent="true"

适用于放在/system/app下的app

 

设置后app提升为系统核心级别，任何情况下不会被kill掉, settings->applications里面也会屏蔽掉stop操作,

设置前 Proc #19: adj=svc  /B 4067b028 255:com.xxx.xxx/10001 (started-services)

# cat /proc/255/oom_adj

4

设置后 PERS #19: adj=core /F 406291f0 155:com.xxx.xxx/10001 (fixed)

# cat /proc/155/oom_adj

-12

 

lowmemorykiller的操作规则比如为

write /sys/module/lowmemorykiller/parameters/adj 0,1,2,4,7,15

write /sys/module/lowmemorykiller/parameters/minfree 2048,3072,4096,6144,7168,8192

 

可以看到，设置persistent后， oom_adj=-12，永远没有机会被lowmemorykiller处理

 

android:persistent 

Whether or not the application should remain running at all times — "true" if it should, and "false" if not. The default value is "false". Applications should not normally set this flag; persistence mode is intended only for certain system applications

 

代码

 

ActivityManagerService.java  
    final ProcessRecord addAppLocked(ApplicationInfo info) {  
        ProcessRecord app = getProcessRecordLocked(info.processName, info.uid);  
  
  
        if (app == null) {  
            app = newProcessRecordLocked(null, info, null);  
            mProcessNames.put(info.processName, info.uid, app);  
            updateLruProcessLocked(app, true, true);  
        }  
  
  
        if ((info.flags&(ApplicationInfo.FLAG_SYSTEM|ApplicationInfo.FLAG_PERSISTENT))  
                == (ApplicationInfo.FLAG_SYSTEM|ApplicationInfo.FLAG_PERSISTENT)) {  
            app.persistent = true;  
            app.maxAdj = CORE_SERVER_ADJ;  
        }  
        if (app.thread == null && mPersistentStartingProcesses.indexOf(app) < 0) {  
            mPersistentStartingProcesses.add(app);  
            startProcessLocked(app, "added application", app.processName);  
        }  
  
  
        return app;  
    }  

 

 

可以看到同时符合FLAG_SYSTEM(/system/app目录)及FLAG_PERSISTENT(android:persistent="true")

的app，设置app.maxAdj = CORE_SERVER_ADJ(-12)，而adj=-12不会被lowmemorykiller处理

 

补充：移动开发 , Android ,