唤醒车机时娱乐屏出现黑屏，卡顿的案例分享

1. 背景

测试在正常操作车机的时候，出现了：唤醒车机时娱乐屏出现连续两次黑屏，且发现系统有卡顿的现象。

2. log分析

low_memory_killer 杀掉adj=100的visible进程，是因为memory 不足导致的。

html 复制代码

行 16839: 10-26 16:22:11.900235   264   264 I lowmemorykiller: Kill 'com.bilibili.bilithings:ijkservice' (19543), uid 10045, oom_adj 200 to free 65668kB
	行 16840: 10-26 16:22:11.900316   264   264 I lowmemorykiller: Reclaimed 65668kB, cache(209812kB) and free(52500kB)-reserved(150240kB) below min(224692kB) for oom_adj 200
	行 16854: 10-26 16:22:11.918705   264   264 I lowmemorykiller: Kill 'com.android.inputmethod' (15307), uid 10020, oom_adj 200 to free 55604kB
	行 16855: 10-26 16:22:11.918735   264   264 I lowmemorykiller: Reclaimed 55604kB, cache(209292kB) and free(73144kB)-reserved(150240kB) below min(224692kB) for oom_adj 200
	行 17672: 10-26 16:22:12.369378   264   264 W lowmemorykiller: Failed to open /proc/11439/oom_score_adj; errno=2: process 11439 might have been killed
	行 18564: 10-26 16:22:12.916724   264   264 I lowmemorykiller: Reclaimed 0kB, cache(234016kB) and free(19076kB)-reserved(150240kB) below min(262144kB) for oom_adj 250
	行 18565: 10-26 16:22:12.916832   264   264 I lowmemorykiller: Suppressed 90 failed kill reports
	行 19690: 10-26 16:22:13.882001   264   264 I lowmemorykiller: Kill 'com.android.launcher' (2036), uid 1000, oom_adj 100 to free 493428kB
	行 19691: 10-26 16:22:13.882084   264   264 I lowmemorykiller: Reclaimed 493428kB, cache(186928kB) and free(12132kB)-reserved(150240kB) below min(187244kB) for oom_adj 100
	行 19692: 10-26 16:22:13.882106   264   264 I lowmemorykiller: Suppressed 29 failed kill reports
	行 19704: 10-26 16:22:13.887833   264   264 I lowmemorykiller: Kill 'com.android.media' (2937), uid 10029, oom_adj 100 to free 226284kB
	行 19705: 10-26 16:22:13.887862   264   264 I lowmemorykiller: Reclaimed 226284kB, cache(183808kB) and free(13916kB)-reserved(150240kB) below min(187244kB) for oom_adj 100
	行 20857: 10-26 16:22:14.882659   264   264 I lowmemorykiller: Reclaimed 0kB, cache(237948kB) and free(12096kB)-reserved(150240kB) below min(262144kB) for oom_adj 250
	行 20858: 10-26 16:22:14.882715   264   264 I lowmemorykiller: Suppressed 94 failed kill reports
	行 21610: 10-26 16:22:15.763508   264   264 I lowmemorykiller: Kill 'com.android.local.scene' (3278), uid 1000, oom_adj 100 to free 136676kB
	行 21611: 10-26 16:22:15.763572   264   264 I lowmemorykiller: Reclaimed 136676kB, cache(185368kB) and free(13676kB)-reserved(150240kB) below min(187244kB) for oom_adj 100
	行 21612: 10-26 16:22:15.763594   264   264 I lowmemorykiller: Suppressed 3 failed kill reports
	行 22183: 10-26 16:22:16.463138   264   264 I lowmemorykiller: Kill 'com.android.energycenter' (3254), uid 10030, oom_adj 100 to free 119084kB
	行 22184: 10-26 16:22:16.463160   264   264 I lowmemorykiller: Reclaimed 119084kB, cache(183628kB) and free(13204kB)-reserved(150240kB) below min(187244kB) for oom_adj 100
	行 22185: 10-26 16:22:16.463167   264   264 I lowmemorykiller: Suppressed 64 failed kill reports
	行 22193: 10-26 16:22:16.477960   264   264 I lowmemorykiller: Kill 'com.android.btphone' (2126), uid 10028, oom_adj 100 to free 67280kB
	行 22194: 10-26 16:22:16.477977   264   264 I lowmemorykiller: Reclaimed 67280kB, cache(180636kB) and free(34372kB)-reserved(150240kB) below min(187244kB) for oom_adj 100
	行 22199: 10-26 16:22:16.481801   264   264 I lowmemorykiller: Kill 'com.android.carplay' (2446), uid 1000, oom_adj 100 to free 66228kB
	行 22200: 10-26 16:22:16.481822   264   264 I lowmemorykiller: Reclaimed 66228kB, cache(178556kB) and free(39916kB)-reserved(150240kB) below min(187244kB) for oom_adj 100
	行 22219: 10-26 16:22:16.499102   264   264 I lowmemorykiller: Kill 'com.android.permissioncontroller' (2322), uid 10043, oom_adj 100 to free 63492kB
	行 22220: 10-26 16:22:16.499117   264   264 I lowmemorykiller: Reclaimed 63492kB, cache(172056kB) and free(99560kB)-reserved(150240kB) below min(187244kB) for oom_adj 100
	行 22230: 10-26 16:22:16.515621   264   264 I lowmemorykiller: Kill 'android.ext.services' (1731), uid 10039, oom_adj 100 to free 54652kB
	行 22231: 10-26 16:22:16.515644   264   264 I lowmemorykiller: Reclaimed 54652kB, cache(167376kB) and free(118736kB)-reserved(150240kB) below min(187244kB) for oom_adj 100
	行 22289: 10-26 16:22:16.535189   264   264 I lowmemorykiller: Kill 'com.android.linkmanager' (2296), uid 1000, oom_adj 100 to free 52544kB

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

可以看到adj=100的定义：VISIBLE_APP_ADJ，从google的描述来看，adj=100的进程是可见activity对应的进程，不应被杀掉。

java 复制代码

    // This is a process bound by the system (or other app) that's more important than services but
    // not so perceptible that it affects the user immediately if killed.
    public static final int PERCEPTIBLE_LOW_APP_ADJ = 250;

    // This is a process hosting services that are not perceptible to the user but the
    // client (system) binding to it requested to treat it as if it is perceptible and avoid killing
    // it if possible.
    public static final int PERCEPTIBLE_MEDIUM_APP_ADJ = 225;

    // 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.
    public static final int PERCEPTIBLE_APP_ADJ = 200;

    // This is a process only hosting activities that are visible to the
    // user, so we'd prefer they don't disappear.
    public static final int VISIBLE_APP_ADJ = 100;
    static final int VISIBLE_APP_LAYER_MAX = PERCEPTIBLE_APP_ADJ - VISIBLE_APP_ADJ - 1;

    // This is a process that was recently TOP and moved to FGS. Continue to treat it almost
    // like a foreground app for a while.
    // @see TOP_TO_FGS_GRACE_PERIOD
    public static final int PERCEPTIBLE_RECENT_FOREGROUND_APP_ADJ = 50;

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

    // This is a process that the system or a persistent process has bound to,
    // and indicated it is important.
    public static final int PERSISTENT_SERVICE_ADJ = -700;

log进程占用内存过大触发low memory

html 复制代码

10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ?? 1650301: logmgr (pid 855) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??   77679: surfaceflinger (pid 497) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??   58900: logd (pid 263) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??   16023: android.hardware.automotive.vehicle@2.0-service (pid 428) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??   15327: media.extractor (pid 764) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??   13763: audioserver (pid 486) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??   12345: media.metrics (pid 767) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??   11470: zygote (pid 389) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??   10143: webview_zygote (pid 1542) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??    7932: mediaserver (pid 769) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??    7912: media.swcodec (pid 781) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??    7103: cameraserver (pid 742) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??    6721: android.hardware.graphics.composer@2.4-service (pid 442) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??    6605: android.hardware.audio.service (pid 274) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??    6383: init (pid 1) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??    6122: zygote64 (pid 388) native
10-26 16:22:13.489428  1111 11527 I ActivityManager:   ntv   ??    5720: media.hwcodec (pid 462) native

Log V等级的log大量打印，导致logd进程来不及输出，占用内存所致。

html 复制代码

	行    89: 10-26 16:22:02.900211   622 16572 V tbox_client: wait heartbeat signal timeout
	行    92: 10-26 16:22:02.900295   622 16572 V tbox_client: BaseMessageInterface
	行    93: 10-26 16:22:02.900319   622 16572 V tbox_client: init BaseMessageInterface new message:0xb400007665043780 data:0xb4000076e50310b0
	行    94: 10-26 16:22:02.900575   622 16572 V tbox_client: wait for heartbeat signal
	行    98: 10-26 16:22:02.900927   622 16123 V tbox_client: ~BaseMessageInterface ~BaseMessageInterface delete message:0xb400007665043780 data:0xb4000076e50310b0
	行   101: 10-26 16:22:02.901545   428 16144 V ANDROID_SOMEIP: SOME/IP-RM [0x0000] received message [NOTIFICATION] on service [0x0301:0x8003:0x0001]
	行   102: 10-26 16:22:02.901622   428 16144 V ANDROID_SOMEIP: Received [NOTIFICATION] message from Client [0x0000] for a Service [0x0301:0x0001] Method [0x8003] with len [33]
	行   103: 10-26 16:22:02.901638   428 16144 V ANDROID_SOMEIP: SOME/IP-SA received message [2] on Service [0x0301:0x0001:0x8003] client [0x0000] len [1]
	行   104: 10-26 16:22:02.901755   428   508 V -BIND   : [COM Callback: 0x0301:0x0001:0x8003]
	行   106: 10-26 16:22:02.902100   428 16144 V ANDROID_SOMEIP: SOME/IP-RM [0x0000] received message [NOTIFICATION] on service [0x0302:0x8001:0x0001]
	行   107: 10-26 16:22:02.902137   428 16144 V ANDROID_SOMEIP: Received [NOTIFICATION] message from Client [0x0000] for a Service [0x0302:0x0001] Method [0x8001] with len [103]
	行   108: 10-26 16:22:02.902202   428 16144 V ANDROID_SOMEIP: SOME/IP-SA received message [2] on Service [0x0302:0x0001:0x8001] client [0x0000] len [71]
	行   109: 10-26 16:22:02.902270   428   508 V -BIND   : [COM Callback: 0x0302:0x0001:0x8001]
	行   211: 10-26 16:22:02.941557   428 16144 V ANDROID_SOMEIP: SOME/IP-RM [0x0000] received message [NOTIFICATION] on service [0x0302:0x8001:0x0001]
	行   212: 10-26 16:22:02.941629   428 16144 V ANDROID_SOMEIP: Received [NOTIFICATION] message from Client [0x0000] for a Service [0x0302:0x0001] Method [0x8001] with len [103]
	行   213: 10-26 16:22:02.941647   428 16144 V ANDROID_SOMEIP: SOME/IP-SA received message [2] on Service [0x0302:0x0001:0x8001] client [0x0000] len [71]
	行   214: 10-26 16:22:02.941731   428 16144 V ANDROID_SOMEIP: SOME/IP-RM [0x0000] received message [NOTIFICATION] on service [0x0301:0x8003:0x0001]
	行   215: 10-26 16:22:02.941753   428 16144 V ANDROID_SOMEIP: Received [NOTIFICATION] message from Client [0x0000] for a Service [0x0301:0x0001] Method [0x8003] with len [33]
	行   216: 10-26 16:22:02.941762   428 16144 V ANDROID_SOMEIP: SOME/IP-SA received message [2] on Service [0x0301:0x0001:0x8003] client [0x0000] len [1]
	行   217: 10-26 16:22:02.941828   428   508 V -BIND   : [COM Callback: 0x0301:0x0001:0x8003]
	行   219: 10-26 16:22:02.941961   428   508 V -BIND   : [COM Callback: 0x0302:0x0001:0x8001]
	行   286: 10-26 16:22:02.964688  1111  1156 V SettingsProvider: callingUid=1000 call([settings, PUT_global, android_car_info_driving_speed, Bundle[{_user=0, value=48}]]) = null
	行   293: 10-26 16:22:02.967693  1111 11173 V SettingsProvider: callingUid=1000 call([settings, GET_global, dropbox_age_seconds, null]) = Bundle[{value=null}]
	行   295: 10-26 16:22:02.967786  1111 11173 V SettingsProvider: callingUid=1000 call([settings, GET_global, dropbox_max_files, null]) = Bundle[{value=null}]
	行   297: 10-26 16:22:02.967866  1111 11173 V SettingsProvider: callingUid=1000 call([settings, GET_global, dropbox_quota_percent, null]) = Bundle[{value=null}]
	行   298: 10-26 16:22:02.968010  1111 11173 V SettingsProvider: callingUid=1000 call([settings, GET_global, dropbox_reserve_percent, null]) = Bundle[{value=null}]
	行   300: 10-26 16:22:02.968181  1111 11173 V SettingsProvider: callingUid=1000 call([settings, GET_global, dropbox_quota_kb, null]) = Bundle[{value=null}]
	行   311: 10-26 16:22:02.971871  1111  5423 V SettingsProvider: callingUid=1000 call([settings, GET_global, com.android.assistant.full_wakeup_free.enable, null]) = Bundle[{value=null}]
	行   313: 10-26 16:22:02.972473  1111 17082 V SettingsProvider: callingUid=1000 call([settings, GET_global, driving_video_limit_key, null]) = Bundle[{value=0}]

logd输出如下log表示logd出现了内存不足的情况：
行 1503: 10-26 16:22:03.451576 0 0 D logd : Kicking blocked reader, pid 855, from LogBuffer::kickMe()
行 1508: 10-26 16:22:03.452153 0 0 D logd : Kicking blocked reader, pid 855, from LogBuffer::kickMe()

3. 修改方案

精简log V的log
工程模式去掉log V的调整入口，不让测试或者正常用户使用。