Re: [Xen-devel] Lots of connections led oxenstored stuck

["Liuqiming (John)" <john.liuqiming@xxxxxxxxxx>]

In oxenstored it use "select" for incoming socket, so I don't think it can 
handle more than 1024 socket connections. 

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxx
> [mailto:xen-devel-bounces@xxxxxxxxxxxxx] On Behalf Of Joe Jin
> Sent: Friday, August 08, 2014 3:01 PM
> To: David Scott; Luis R. Rodriguez; Ian Jackson
> Cc: xen-devel
> Subject: [Xen-devel] Lots of connections led oxenstored stuck
> 
> Hi,
> 
> During internal test on Xen-4.3-stable we found sometime when restarted
> Xen, it stuck and does not response any request, xenstored.log filled
> out below stuff:
> [20140702T21:00:41.564Z|error|xenstored] caught exception
> Unix.Unix_error(15, "accept", "")
> 
> I created reproducer which will create 2000 connections to oxenstored,
> after
> ran the reproducer, "xm list --long" will stuck, oxenstored does not
> response anymore, same test case passed when use xenstored, any input
> will appreciate!
> 
> /*
>  * This program used to test oxenstored connections stuck issue.
>  * please compile by below command:
>  *    gcc -o client client.c -lpthread
>  */
> #include <stdio.h>
> #include <sys/socket.h>
> #include <sys/un.h>
> #include <unistd.h>
> #include <string.h>
> #include <pthread.h>
> #include <stdlib.h>
> #include <errno.h>
> 
> 
> void *main_thread(void *arg)
> {
>       struct sockaddr_un address;
>       int socket_fd, nbytes;
>       char buffer[256];
>       int i;
>       extern int errno;
> 
>       memcpy(&i, arg, sizeof(i));
>       socket_fd = socket(PF_UNIX, SOCK_STREAM, 0);
>       if (socket_fd < 0) {
>               fprintf(stderr, "socket() %dth failed, errno=%d\n", i, errno);
>               return;
>       }
>       fprintf(stderr, "socket() %dth ok!\n", i);
> 
>       /* start with a clean address structure */
>       memset(&address, 0, sizeof(struct sockaddr_un));
> 
>       address.sun_family = AF_UNIX;
>       snprintf(address.sun_path, 1024, "/var/run/xenstored/socket");
> 
>       if (connect(socket_fd,
>                   (struct sockaddr *) &address,
>                   sizeof(struct sockaddr_un)) != 0) {
>               fprintf(stderr, "connect() %d failed, error=%d", i, errno);
>               return;
>       }
>       fprintf(stderr, "connec() %dth ok!\n", i);
> 
>       while (1)
>               sleep(1);
>       if (arg) {
>               free(arg);
>               arg = NULL;
>       }
> 
>       return;
> }
> 
> int main(void)
> {
>       int i;
>       for (i = 0; i < 2000; i++) {
>               void *arg = malloc(sizeof(i));
>               memset(arg, 0, sizeof(i));
>               memcpy(arg, &i, sizeof(i));
>               pthread_t thread;
>               if (pthread_create(&thread, NULL, main_thread, arg) != 0) {
>                       perror("pthread_create:");
>                       break;
>               }
>       }
>       /* Wait all children exit */
>       sleep(3);
>       return 0;
> }
> /* end */
> 
> Thanks,
> Joe
> 
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