select: Interrupted system call

select: Interrupted system call

[Gerald Waugh]

I am attempting to run a program that manages several tcp/ip connections
It runs for a while then I get the subject error, also below
select: Interrupted system call
I think it may be because I am not handling any signals.
How do I fix it? Asn which signals should I be catching?
TIA

-- 
Gerald Waugh : Registered Linux user # 255245
http://www.frontstreetnetworks.com
Front Street Networks LLC - ph. 203.785.0699
229 Front Street, Ste. #C, New Haven, CT, United States of America
11:01am up 36 days, 18:28, 3 users, load average: 1.09, 1.18, 1.14

Re: select: Interrupted system call

[Glynn Clements]

Gerald Waugh wrote:

> I am attempting to run a program that manages several tcp/ip connections
> It runs for a while then I get the subject error, also below
> select: Interrupted system call
> I think it may be because I am not handling any signals.

select() returns EINTR if a signal is caught and handled. If a signal
is caught but not handled, it will either do nothing, or terminate the
process, depending upon the signal.

> How do I fix it?

If select() indicates an error, check whether it is EINTR. If it is,
ignore it. Alternatively, you can block the signal (with sigprocmask())
for the duration of the call to select().

-- 
Glynn Clements <glynn.clements@virgin.net>

Re: select: Interrupted system call

[Gerald Waugh]

On Saturday 27 April 2002 03:22 pm, Glynn Clements wrote:
> Gerald Waugh wrote:
> +	#include <errno.h>
>
>            rdsocks = select(hs+1, &socks, (fd_set *) 0,
>             (fd_set *) 0, &timeout);
>
> -          if (rdsocks < 0) {
> +          if (rdsocks < 0 && errno != EINTR) {
>
>                    perror("select");
>                    continue;
>                    //  exit(EXIT_FAILURE);
>            }
>
> > I commented out the exit(EXIT_FAILURE); and added continue;
> > but I still get   " select: Interrupted system call ", it keeps running
> > and managing the connections...
> > Seems like I should be able to find out whats causing it,
> > Interrupted system call   Does not seem to tell me much.
> You should handle this case rather than trying to prevent it.
>
> Prevention is fragile; if the program is subsequently changed to catch
> a new signal (possibly via a library function), the problem will
> re-appear.
>
> Handling this case will ensure that the program is robust. Terminating
> due to transient errors isn't a good idea.

I was testing to see if I could keep it going, I did similar to your 
suggestion:
Only I did  if (rdsocks < 0 && rdsocks != EINTR)  {
And I was still getting  a printout of  " select: Interrupted system call "
Now I'll try 
if (rdsocks < 0 && errno != EINTR) {

I would really like to know why select()
gets that  Interrupted system call


-- 
Gerald Waugh : Registered Linux user # 255245
http://www.frontstreetnetworks.com
Front Street Networks LLC - ph. 203.785.0699
229 Front Street, Ste. #C, New Haven, CT, United States of America
4:32pm up 36 days, 23:59, 3 users, load average: 0.80, 1.14, 1.27

Re: select: Interrupted system call

[Glynn Clements]

Gerald Waugh wrote:

> I would really like to know why select()
> gets that  Interrupted system call

If you have "strace", that should show which signal is being caught.

-- 
Glynn Clements <glynn.clements@virgin.net>