C/Zombies
From Attie's Wiki
(Difference between revisions)
| (8 intermediate revisions by 2 users not shown) | |||
| Line 1: | Line 1: | ||
The code below will quickly tidy up after zombie children, and at the same time check for incoming data. | The code below will quickly tidy up after zombie children, and at the same time check for incoming data. | ||
| − | Assume <code>sock</code> is the file descriptor that you wish to read from | + | * Assume <code>sock</code> is the file descriptor that you wish to read from<br> |
| − | < | + | * <code>children</code> is incremented when you call <code>fork()</code> |
| − | + | <source lang="c"> | |
| − | + | /* tidy up after children, but accept new data if its there! */ | |
| − | + | while (children) { | |
| − | + | int pid, status, read; | |
| − | + | struct timeval timeout; | |
| + | fd_set toset; | ||
| − | + | /* check if any children have become zombies! */ | |
| − | + | pid = waitpid(-1,&status,WNOHANG | WUNTRACED); | |
| − | + | if (pid > 0) { | |
| − | + | children--; | |
| − | + | printf("*** Child Died *** PID: %-6d Status: %-3d Children: %-2d\n",pid,WEXITSTATUS(status),children); | |
| − | + | /* if there are no children left, will break | |
| − | /* if there are no children left, | + | if there are more zombie children will tidy up before looking for data */ |
| − | + | continue; | |
| + | } | ||
| − | + | /* timeout on the socket every 0.5sec */ | |
| − | + | memset(&timeout,0,sizeof(timeout)); | |
| − | + | timeout.tv_usec = 500000; | |
| − | + | FD_ZERO(&toset); | |
| − | + | FD_SET(sock,&toset); | |
| − | + | /* check if there is data in the socket to be read... */ | |
| − | + | if ((read = select(sock+1,&toset,NULL,NULL,&timeout)) == -1) { | |
| − | + | perror("select()"); | |
| − | + | break; | |
| − | + | } else if (read != 0) { | |
| − | + | /* something can be read! */ | |
| − | + | break; | |
| − | + | ||
} | } | ||
| − | </ | + | } |
| + | </source> | ||
Latest revision as of 17:06, 14 February 2013
The code below will quickly tidy up after zombie children, and at the same time check for incoming data.
- Assume
sockis the file descriptor that you wish to read from
-
childrenis incremented when you callfork()
/* tidy up after children, but accept new data if its there! */ while (children) { int pid, status, read; struct timeval timeout; fd_set toset; /* check if any children have become zombies! */ pid = waitpid(-1,&status,WNOHANG | WUNTRACED); if (pid > 0) { children--; printf("*** Child Died *** PID: %-6d Status: %-3d Children: %-2d\n",pid,WEXITSTATUS(status),children); /* if there are no children left, will break if there are more zombie children will tidy up before looking for data */ continue; } /* timeout on the socket every 0.5sec */ memset(&timeout,0,sizeof(timeout)); timeout.tv_usec = 500000; FD_ZERO(&toset); FD_SET(sock,&toset); /* check if there is data in the socket to be read... */ if ((read = select(sock+1,&toset,NULL,NULL,&timeout)) == -1) { perror("select()"); break; } else if (read != 0) { /* something can be read! */ break; } }
