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Top Forums Programming select() system call takes longer than the timeout specified Post 302408919 by jim mcnamara on Wednesday 31st of March 2010 08:17:25 AM
Old 03-31-2010
There is clearly something else in your code/system that is not shown. select() was and is actively used as a very reliable way to implement sleep(), usleep() and other "sleep" calls on old systems that do not support them. Almost categorically select() is not directly causing your problem - if what you posted is correct.

If your process has low priority or is running as a normal process on a realtime system you may get extended waits. Not 120 seconds.

If you are doing writes on the fd select is waiting on even with huge (multi-GB) data elements I would still find 120 seconds hard to believe. It looks like you are calling curl - so it is probably a linux box right?

We need: OS version, kernel version, and what type of system you have - realtime, desktop, etc.

Have you traced your code and watched it wait in select() 120 seconds, for example?

---------- Post updated 03-31-10 at 06:17 ---------- Previous update was 03-30-10 at 20:27 ----------

Q:
int maxfd=some_fixed_value (?)

where is int maxfd initialized?
 

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SLEEP(3)						   BSD Library Functions Manual 						  SLEEP(3)

NAME
sleep -- suspend thread execution for an interval measured in seconds LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <unistd.h> unsigned int sleep(unsigned int seconds); DESCRIPTION
The sleep() function suspends execution of the calling thread until either seconds seconds have elapsed or a signal is delivered to the thread and its action is to invoke a signal-catching function or to terminate the thread or process. System activity may lengthen the sleep by an indeterminate amount. This function is implemented using nanosleep(2) by pausing for seconds seconds or until a signal occurs. Consequently, in this implementa- tion, sleeping has no effect on the state of process timers, and there is no special handling for SIGALRM. RETURN VALUES
If the sleep() function returns because the requested time has elapsed, the value returned will be zero. If the sleep() function returns due to the delivery of a signal, the value returned will be the unslept amount (the requested time minus the time actually slept) in seconds. SEE ALSO
nanosleep(2), usleep(3) STANDARDS
The sleep() function conforms to ISO/IEC 9945-1:1990 (``POSIX.1''). HISTORY
A sleep() function appeared in Version 7 AT&T UNIX. BSD
February 13, 1998 BSD
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