转载自我的CSDN Blog
有客户反馈视频播放一段时间就卡住了，且是必现。从logcat信息上发现是mediaserver进程异常崩溃了，Log如下：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 ABI: 'arm' pid: 246, tid: 1710, name: DecoderAudio >>> /system/bin/mediaserver <<< signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x0 r0 00000000 r1 89c17780 r2 00001180 r3 00000000 r4 b79822a0 r5 00001200 r6 89c17704 r7 89c17740 r8 89c17738 r9 00000000 sl 03598a78 fp 00000000 ip b64234c8 sp 89c176f8 lr b63eaf75 pc b6a8794c cpsr 200f0010 d0 f099f6d8f041f6c2 d1 f108f776f10ef738 d2 f08af7eff0a6f79c d3 f0f3f71df0c6f7ef d4 f171f601f106f624 d5 f366f728f260f699 d6 f5a8f7bff45ff779 d7 f676f741f6c2f7d2 d8 3ef5d867c3ece2a5 d9 412e848000000000 d10 0000000000000000 d11 0000000000000000 d12 0000000000000000 d13 0000000000000000 d14 0000000000000000 d15 0000000000000000 d16 0000000000000000 d17 0000000000000000 d18 3ff0000000000000 d19 4091780000000000 d20 be5ae5d13e0705cf d21 4037f9dcb5112287 d22 bf2a017308872714 d23 3de5d93a5acfd57c d24 3ec71de357b1fe7d d25 3e21e0e0299e8cc5 d26 4037f9dcb5112287 d27 40032e4a2a741b9f d28 3f895d470d6e9486 d29 3f895d470d6e9486 d30 3fe797c6a435ce85 d31 400921fb54400000 scr 68000012 backtrace: #00 pc 0001694c /system/lib/libc.so (memcpy+112) #01 pc 00042f71 /system/lib/librkffplayer.so (_ZN7android13RkAudioPlayer10queueAudioEPsix+56) #02 pc 0004d509 /system/lib/librkffplayer.so (_ZN7android9FFMPlayer6decodeEPsixxiPv+652) #03 pc 0003167f /system/lib/librkffplayer.so (_ZN12DecoderAudio17SoftDecodeProcessEP8AVPacket+910) #04 pc 00030ea9 /system/lib/librkffplayer.so (_ZN12DecoderAudio6decodeEPv+280) #05 pc 00034203 /system/lib/librkffplayer.so (_ZN12PlayerThread11startThreadEPv+46) #06 pc 000417c7 /system/lib/libc.so (_ZL15__pthread_startPv+30) #07 pc 00019313 /system/lib/libc.so (__start_thread+6)
在导致异常的代码附近添加LOG确认了是malloc调用返回空指针，内存分配失败了，但查看kmsg并未发现LMK或者OOM出现。
查看系统limit没有问题：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 root@rk3288:/ # ulimit -Sa time(cpu-seconds) unlimited file(blocks) unlimited coredump(blocks) 0 data(KiB) unlimited stack(KiB) 8192 lockedmem(KiB) 64 nofiles(descriptors) 1024 processes 10576 sigpending 10576 msgqueue(bytes) 819200 maxnice 40 maxrtprio 0 resident-set(KiB) unlimited address-space(KiB) unlimited root@rk3288:/ # ulimit -Ha time(cpu-seconds) unlimited file(blocks) unlimited coredump(blocks) unlimited data(KiB) unlimited stack(KiB) unlimited lockedmem(KiB) 64 nofiles(descriptors) 4096 processes 10576 sigpending 10576 msgqueue(bytes) 819200 maxnice 40 maxrtprio 0 resident-set(KiB) unlimited address-space(KiB) unlimited
再看mediaserver进程，发现它的address-space被限制在1370941585 bytes:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 130|root@rk3288:/ # cat /proc/4506/limits Limit Soft Limit Hard Limit Units Max cpu time unlimited unlimited seconds Max file size unlimited unlimited bytes Max data size unlimited unlimited bytes Max stack size 8388608 unlimited bytes Max core file size 0 unlimited bytes Max resident set unlimited unlimited bytes Max processes 10576 10576 processes Max open files 1024 4096 files Max locked memory 65536 65536 bytes Max address space 1370941585 unlimited bytes Max file locks unlimited unlimited locks Max pending signals 10576 10576 signals Max msgqueue size 819200 819200 bytes Max nice priority 40 40 Max realtime priority 0 0 Max realtime timeout unlimited unlimited us
通过命令修改进程的limit，重新测试视频正常:
google从Android6.0开始，对mediaserver进程的虚拟内存大小做出了限制，默认值是系统总内存的65%，这在普通的手机及平板等产品上没有问题，但在一些定制的产品，比如低内存的电视盒子，或者是多路视频同时播放的场景，这些产品在播放视频时候对内存的消耗在系统中占比可能超过65%，从而触发limit机制导致内存申请失败。