SH：內存不足的系統調用

Question

我運行在基於ARM的板下面的代碼：

sh: out of memory 
StartStreamer: command=[/usr/bin/gst-launch-0.10 imxv4l2src ! imxv4l2sink &], status:256 
Segmentation fault 
Rebooting:35584 
StopStreamer: command=[killall gst-launch-0.10], status = 11 
Rebooting:11 
Loop Count:26 
sh: relocation error: sh: symbol free, version GLIBC_2.4 not defined in file libc.so.6 with link time reference 
sh: relocation error: sh: symbol free, version GLIBC_2.4 not defined in file libc.so.6 with link time reference 
StartStreamer: command=[/usr/bin/gst-launch-0.10 imxv4l2src ! imxv4l2sink &], status:32512 
Rebooting:11 
killall: gst-launch-0.10: no process killed 
StopStreamer: command=[killall gst-launch-0.10], status = 11 
Rebooting:11 
Loop Count:27 
StartStreamer: command=[/usr/bin/gst-launch-0.10 imxv4l2src ! imxv4l2sink &], status:32512 
Rebooting:32512 

可以：

void MainLoop() 
{ 
    char command[256]; 
    int ret = 0; 
    int loopCount = 0; 
    while(1) 
    { 
     memset(command, '\0', sizeof(command)); 
     sprintf(command, "/usr/bin/gst-launch-0.10 imxv4l2src ! imxv4l2sink &"); 
     ret = system(command); 
     printf("StartStreamer: command=[%s], status:%d\n", command, ret); 
     if (ret != 0) 
     { 
      ret = system("reboot"); 
      printf("Rebooting:%d\n", ret); 
     } 
     sleep(15); 
     memset(command, '\0', sizeof(command)); 
     sprintf(command, "killall gst-launch-0.10"); 
     ret = system(command); 
     printf("StopStreamer: command=[%s], status = %d\n", command, ret); 
     if (ret != 0) 
     { 
      ret = system("reboot"); 
      printf("Rebooting:%d\n", ret); 
     } 
     sleep(15); 
     loopCount++; 
     printf("Loop Count:%d\n", loopCount); 

    } 
} 

運行一些隨機循環我收到以下錯誤後你請告訴我什麼是「sh：內存不足」，意思是說，是因爲系統調用太多。而且，它的奇怪的是我得到glibc重定位錯誤...

我已經從C應用程序修改爲Bash sc RIPT：

#!/bin/ash 
count=0 
    while [ true ];do 
      echo "Starting Streamer" 
     /usr/bin/gst-launch-0.10 imxv4l2src ! imxv4l2sink & 
      sleep 15 
      echo "Stopping Streamer" 
      killall gst-launch-0.10 
      sleep 15 
      count=$((count+1)) 
      echo $count 
    done 

而對於一些循環，我得到以下錯誤後運行：

*錯誤/bin/sh': double free or corruption (out): 0x0028ebf8 *** *** Error in/bin/sh的'：的malloc（）：內存破壞：0x0028edf8 *

Answer 1

Can you please tell me what does "sh: Out of Memory" means, is it because of too many system calls.

從system手冊頁：

The system() library function uses fork(2) to create a child 
    process that executes the shell command specified in command using 
    execl(3) as follows: 

     execl("/bin/sh", "sh", "-c", command, (char *) 0); 

    system() returns after the command has been completed. 

我會說這就是爲什麼你看到這條消息。你顯然已經用盡了fork部分的資源。無論這是進入rlimit還是僅僅在內存中運行（更可能），很難說清楚。

所以基本上你有一個主循環，調用system，「底層」創建你的進程的副本，並將二進制文件（execl部分）複製到副本中。哦，你試圖killall第一個過程（再次system）。不幸的是，信號並不能保證是可靠的，但通常會收到。另一個複雜的問題是，你處於調度程序的擺佈之中，當你認爲它可能不會運行該進程時。

這將會是更好的訪問使用更原始的fork/exec功能這一功能 - 至少你有PID到無killall的開銷發送信號。