Android adb 查看进程优先级

简介

有时候我们想要知道某个app在系统进程中的优先级，有什么办法可以查看吗？答案是有的，通过adb命令的方式，我们可以获取进程在系统中的优先级。下面来看下具体操作：

步骤

第一步：获取进程pid

C:\Users\xxx>adb shell ps

USER     PID   PPID  VSIZE  RSS     WCHAN    PC         NAME
...
u0_a3     679   109   471124 39808 ffffffff 00000000 S com.android.systemui
u0_a13    846   109   302108 19832 ffffffff 00000000 S com.android.inputmethod.p
inyin
radio     889   109   317536 23220 ffffffff 00000000 S com.android.phone
u0_a9     917   109   487980 85124 ffffffff 00000000 S com.xxx.xxx
...

通过adb shell ps获取相应包的pid，例如我要获取·com.xxx.xxx·这个包的pid，其值即为917。

第二步：查看进程优先级

C:\Users\solo>adb shell

shell@imx6:/ $ cat proc/917/oom_adj
0
shell@imx6:/ $

在proc目录下我们找到对应的pid文件夹，查看里面的oom_adj就可以获取到进程的优先级了。我们可以看到pid为917的进程其值为0。0表示该进程是正在前台运行。这些值的具体定义在ProcessList.java这个文件中。

frameworks/base/services/java/com/android/server/am/ProcessList.java

/**
 * Activity manager code dealing with processes.
 */
final class ProcessList {
    // OOM adjustments for processes in various states:

    // Adjustment used in certain places where we don't know it yet.
    // (Generally this is something that is going to be cached, but we
    // don't know the exact value in the cached range to assign yet.)
    static final int UNKNOWN_ADJ = 16;

    // This is a process only hosting activities that are not visible,
    // so it can be killed without any disruption.
    static final int CACHED_APP_MAX_ADJ = 15;
    static final int CACHED_APP_MIN_ADJ = 9;

    // The B list of SERVICE_ADJ -- these are the old and decrepit
    // services that aren't as shiny and interesting as the ones in the A list.
    static final int SERVICE_B_ADJ = 8;

    // This is the process of the previous application that the user was in.
    // This process is kept above other things, because it is very common to
    // switch back to the previous app.  This is important both for recent
    // task switch (toggling between the two top recent apps) as well as normal
    // UI flow such as clicking on a URI in the e-mail app to view in the browser,
    // and then pressing back to return to e-mail.
    static final int PREVIOUS_APP_ADJ = 7;

    // This is a process holding the home application -- we want to try
    // avoiding killing it, even if it would normally be in the background,
    // because the user interacts with it so much.
    static final int HOME_APP_ADJ = 6;

    // This is a process holding an application service -- killing it will not
    // have much of an impact as far as the user is concerned.
    static final int SERVICE_ADJ = 5;

    // This is a process with a heavy-weight application.  It is in the
    // background, but we want to try to avoid killing it.  Value set in
    // system/rootdir/init.rc on startup.
    static final int HEAVY_WEIGHT_APP_ADJ = 4;

    // This is a process currently hosting a backup operation.  Killing it
    // is not entirely fatal but is generally a bad idea.
    static final int BACKUP_APP_ADJ = 3;

    // This is a process only hosting components that are perceptible to the
    // user, and we really want to avoid killing them, but they are not
    // immediately visible. An example is background music playback.
    static final int PERCEPTIBLE_APP_ADJ = 2;

    // This is a process only hosting activities that are visible to the
    // user, so we'd prefer they don't disappear.
    static final int VISIBLE_APP_ADJ = 1;

    // This is the process running the current foreground app.  We'd really
    // rather not kill it!
    static final int FOREGROUND_APP_ADJ = 0;

    // This is a system persistent process, such as telephony.  Definitely
    // don't want to kill it, but doing so is not completely fatal.
    static final int PERSISTENT_PROC_ADJ = -12;

    // The system process runs at the default adjustment.
    static final int SYSTEM_ADJ = -16;

    // Special code for native processes that are not being managed by the system (so
    // don't have an oom adj assigned by the system).
    static final int NATIVE_ADJ = -17;
}

通过上面文件我们可以知道oom_adj的值越小，其优先级越高。除了，上面使用ps和cat的方式。接下来我们看下另一种是查看进程优先级的方法。

另一种方法：通过dumpsys的方式

C:\Users\solo>adb shell dumpsys activity processes

*APP* UID 10009 ProcessRecord{41940070 917:com.xxx.xxx/u0a9}
    user #0 uid=10009
    dir=/system/app/xxx.apk publicDir=/system/app/xxx.apk data=/data/user/0/com.xxx.xxx
    packageList={com.xxx.xxx}
    compat={160dpi always-compat}
    thread=android.app.ApplicationThreadProxy@4196b5e0
    pid=917 starting=false
    lastActivityTime=-47m54s745ms lastPssTime=-1m51s601ms nextPssTime=+8s362ms
    adjSeq=880 lruSeq=0 lastPss=76916 lastCachedPss=0
    keeping=true cached=false empty=false
    oom: max=16 curRaw=0 setRaw=0 cur=0 set=0
    curSchedGroup=-1 setSchedGroup=-1 systemNoUi=false trimMemoryLevel=0
    curProcState=2 repProcState=2 pssProcState=2 setProcState=2 lastStateTime=-58m39s814ms
    hasShownUi=true pendingUiClean=true hasAboveClient=false
    hasClientActivities=false foregroundActivities=true
    lastRequestedGc=-58m39s817ms lastLowMemory=-58m39s817ms reportLowMemory=false
    Activities:
      - ActivityRecord{4193b008 u0 com.xxx.xxx/.HomeMain t1}
    Connected Providers:
      - 417e1038/com.android.providers.settings/.SettingsProvider->917:com.spd.home/u0a9 s1/1 u0/0 +58m33s751ms
    Receivers:
      - ReceiverList{4190ac08 917 com.xxx.xxx/10009/u0 remote:41a8bba8}
      - ReceiverList{419c9898 917 com.xxx.xxx/10009/u0 remote:41991410}
      - ReceiverList{419e2228 917 com.xxx.xxx/10009/u0 remote:4196dfb8}
      - ReceiverList{419e5a70 917 com.xxx.xxx/10009/u0 remote:418b6e20}
      - ReceiverList{419ea018 917 com.xxx.xxx/10009/u0 remote:419b8820}
      - ReceiverList{41a41510 917 com.xxx.xxx/10009/u0 remote:419970b8}

通过dumpsys命令，找到对应的包名下的进程信息，我们可以看到oom: max=16 curRaw=0 setRaw=0 cur=0 set=0这一行。cur=0就是该进程的优先级。

总结

通过上面两种方式，我们都可以获取到相关进程的优先级。