[cs631apue] Forking too many processes.

[hao wu]

"The problem was that before the child process was able to "accept(...)"
the connection the parent process forks another process as the connection
is still in the queue."

it is better to do the "accept" in the main process
here is my logic:

//main process
while {
   accept(....)
   //a new client coming:
   fork a child process handle this connection
   continue; //main process waiting for another connection
}

-Hao



On Mon, Nov 4, 2013 at 2:48 PM, lbustama <lbustama at stevens.edu> wrote:

> By the way here is part of the code. Just in case I'm doing something
> wrong:
>
> listen(sock, 5);
> 184     do {
> 185         FD_ZERO(&ready);
> 186         FD_SET(sock, &ready);
> 187         to.tv_sec = 5;
> 188         to.tv_usec = 0;
> 189         if (select(sock + 1, &ready, 0, 0, &to) < 0) {
> 190             perror("select");
> 191             continue;
> 192         }
> 193         if (FD_ISSET(sock, &ready)) {
> 194
> 195             pid_t pid;
> 196             if((pid = fork()) < 0)
> 197             {
> 199                 perror("fork error");
> 200             }
> 201             if(pid == 0) /*child*/
> 202             {
> 203                 /* variables for client information */
> 204                 socklen_t client_length;
> 205                 struct sockaddr_in client;
> 206                 unsigned int client_port;
> 207
> 208                 client_length = sizeof(client);
> 209                 msgsock = accept(sock, (struct sockaddr *)&client,
> 210                         &client_length);
>                     ....
> 230                 exit(EXIT_SUCCESS);
> 231             }
> 232             else
> 233             {
> 234                 printf("forked pid: %d\n",pid);
> 235             }
> 236         }
> 243     } while (TRUE);
>
> Thanks,
>
> Luis
>
>
> On 11/04/2013 2:43 PM, lbustama wrote:
>
>> Hi,
>>
>> When a new connection comes in to the server I fork a new process to
>> take care of the new connection.
>>
>> I was having an issue after forking the new process.
>> The problem was that before the child process was able to
>> "accept(...)" the connection the parent process forks another process
>> as the connection is still in the queue.
>>
>> macbookpro:HW3$ ./sws &
>> [2] 6832
>>
>> macbookpro:HW3$ Server listening on IP address 0.0.0.0 and port# 8080
>> forked pid: 6834
>> 127.0.0.1#62858: Connected:
>> forked pid: 6835
>>
>> macbookpro:HW3 Luis$ !net
>> netstat -na | grep 8080
>> tcp4       0      0  127.0.0.1.8080         127.0.0.1.62858
>>  ESTABLISHED
>> tcp4       0      0  127.0.0.1.62858        127.0.0.1.8080
>> ESTABLISHED
>> tcp4       0      0  *.8080                 *.*                    LISTEN
>> macbookpro:HW3 Luis$
>>
>> ^^^ 1 active connection
>>
>> macbookpro:HW3$ ps -o pid,ppid,comm | grep sws
>>  6832  6556 ./sws
>>  6834  6832 ./sws
>>  6835  6832 ./sws
>>
>>
>>
>> ^^^ 2 new processes for 1 request
>>
>>
>> The way I got around this was to put the parent process to sleep for 1
>> second, which will allow the child to grab the new connection.
>>
>> I was wondering if there is a better way to do this? what if your web
>> server receives several connections per second. Only 1 connection is
>> handled every second, which is obviously not good.
>>
>> Thanks,
>>
>> Luis
>>
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