[Libevent-users] busy waiting on AIX (timercmp bug)
Hi, I just have a longish debugging session behind me finding out why a process is doing so many poll()s without doing real work. But this only happens on AIX. It turns out that the timercmp macro in combination with = operator does not work. (used in event.c in libevent-1.4.2-rc2) This is the definition on AIX: /* * Operations on timevals. * * Note that timercmp only works for cmp values of !=, , and . */ ... #define timercmp(tvp, fvp, cmp) \ ((tvp)-tv_sec cmp (fvp)-tv_sec || \ (tvp)-tv_sec == (fvp)-tv_sec \ (tvp)-tv_usec cmp (fvp)-tv_usec) - Here the definition of timercmp on Linux: /* Convenience macros for operations on timevals. NOTE: `timercmp' does not work for = or =. */ ... # define timercmp(a, b, CMP) \ (((a)-tv_sec == (b)-tv_sec) ? \ ((a)-tv_usec CMP (b)-tv_usec) : \ ((a)-tv_sec CMP (b)-tv_sec)) Note that the Linux definition has the same comment about the compare operator as the AIX one. But the comment seems to predate the Linux definition. I found no official documentation if timercmp should support = or =. I would suggest using always the libevent definition of timercmp, without ever using the system one. Jörg ___ Libevent-users mailing list Libevent-users@monkey.org http://monkeymail.org/mailman/listinfo/libevent-users
Re: [Libevent-users] busy waiting on AIX (timercmp bug)
On Mon, Mar 09, 2009 at 01:57:46PM +0100, Richter, J?rg wrote: [...] Note that the Linux definition has the same comment about the compare operator as the AIX one. But the comment seems to predate the Linux definition. I'd guess that the comment is there because, if you're writing a portable program, you need to make sure that you don't use timercmp with =/=, even if it _does_ happen to work on Linux. [...] I found no official documentation if timercmp should support = or =. I would suggest using always the libevent definition of timercmp, without ever using the system one. That's a good idea! We already did it back in 1.4.4, which was released last May. The latest stable libevent release is 1.4.9. yrs, -- Nick ___ Libevent-users mailing list Libevent-users@monkey.org http://monkeymail.org/mailman/listinfo/libevent-users
