socket “read” hanging if the MacBook sleeps more than 10 minutes
socket “read” hanging if the MacBook sleeps more than 10 minutes
- Subject: socket “read” hanging if the MacBook sleeps more than 10 minutes
- From: Sabyasachi Ruj <email@hidden>
- Date: Thu, 5 Nov 2009 19:39:06 +0530
I am writing an app, where a socket is connecting to a host and
downloading a file. The application runs in Mac.
Now, while the app is downloading, if I put the MacBook in sleep mode
for more than 10 minutes, 60% of the time the app hangs when the
computer wakes up.
The stack trace shows that, it has hanged in the "read" call. I am
able to reproduce this with a sample program also. Below, I have
pasted the code of the sample program and the stack where it is
hanging. How to solve this hanging?
Also, this is not just TCP/IP waiting that will come out in few
minutes. I have waited for more than 12 hours, it did not come out.
The stack trace: -
Call graph:
2466 Thread_2507
2466 start
2466 read$UNIX2003
2466 read$UNIX2003
The program :-
#include <stdio.h>
#include <string.h>
#include <netdb.h>
#include <sys/socket.h>
#include <unistd.h>
#define buflen 131072
unsigned int portno = 80;
char hostname[] = "192.168.1.9";
int main()
{
int sd = socket(AF_INET, SOCK_STREAM, 0); /* init socket descriptor */
struct sockaddr_in sin;
struct hostent *host = gethostbyname(hostname);
char buf[buflen];
int len;
int ret;
FILE *fp;
int i;
if(sd == -1){
printf("Could not create client socket\n");
return 1;
}
/*set keep alive*/
int optval = 1;
int optlen = sizeof(optval);
ret = setsockopt(sd, SOL_SOCKET, SO_KEEPALIVE, &optval, optlen);
if(ret != 0){
printf("could not set socket option.\n");
return 1;
}
/*** PLACE DATA IN sockaddr_in struct ***/
memcpy(&sin.sin_addr.s_addr, host->h_addr, host->h_length);
sin.sin_family = AF_INET;
sin.sin_port = htons(portno);
/*** CONNECT SOCKET TO THE SERVICE DESCRIBED BY sockaddr_in struct ***/
if (connect(sd, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
perror("connecting");
return 1;
}
char *str = "GET /general-log.exe / HTTP/1.0\n\n";
ret = write(sd, str, strlen(str));
if(ret < 0){
printf("error while writing\n");
return 1;
}
fp = fopen("downloaded.file", "wb+");
if(fp == NULL){
printf("not able to open the file.\n");
return 1;
}
i = 0;
while ((len = read(sd, buf, buflen)) > 0) {
printf("%d\t%d\n", i++, len);
fwrite(buf, len, 1, fp); //we should check for return
}
if(len < 0){
printf("Error while reading\n");
}
fclose(fp);
close(sd);
return 0;
}
--
Sabyasachi
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