On Tue, Jun 18, 2013 at 4:44 PM, Glenn Fowler <[email protected]> wrote: [snip] > On Tue, 18 Jun 2013 12:28:02 +0200 Cedric Blancher wrote: >> On 18 June 2013 04:34, Glenn Fowler <[email protected]> wrote: [snip] > Real-time signals are distinguished by the following: > > 1. Multiple instances of real-time signals can be queued. By > contrast, if multiple instances of a standard signal are > delivered while that signal is currently blocked, then only one > instance is queued. > > 3. Real-time signals are delivered in a guaranteed order. Multiple > real-time signals of the same type are delivered in the order > they were sent. If different real-time signals are sent to a > process, they are delivered starting with the lowest-numbered > signal. (I.e., low-numbered signals have highest priority.) By > contrast, if multiple standard signals are pending for a process, > the order in which they are delivered is unspecified. > > { USR1 USR2 } are standard signals > while the respective signal handler is executing the signal is blocked > (1.) means that if a bunch of USR1's arrive while USR1 is being handled > all but one are dropped (in other words, only one of many is queued) > > so for a test with a storm of USR1's one would expect a wide range of > values for a USR1 caught counter -- such a test should use RTMIN..RTMAX > for deterministinc results -- determinism seems to be the rationale for > adding RTMIN..RTMAX in the first place
Erm... just curious: If I use "truss" on a 64bit ast-ksh.2013-06-13 binary I see a lot of these two syscalls being issued when using the "SIGUSR1/SIGUSR2 signal storm"-demo: -- snip -- sigaction(SIGCLD, 0xFFFFFFFF7FFFDEE0, 0xFFFFFFFF7FFFDFD8) = 0 lwp_sigmask(SIG_SETMASK, 0x00000000, 0x00000000) = 0xFFBFFEFF [0x0000FFFF] -- snip -- ... why are they neccesary ? Technically the signal traps are set once at the beginning of the script and are then no longer touched... why does the shell then has to alter the signal masks over and over again when the signals are put in a queue anyway (yes, yes... I know... SIGCHLD and SIGALRM are not handled that way (yet)) ? ---- Bye, Roland -- __ . . __ (o.\ \/ /.o) [email protected] \__\/\/__/ MPEG specialist, C&&JAVA&&Sun&&Unix programmer /O /==\ O\ TEL +49 641 3992797 (;O/ \/ \O;) _______________________________________________ ast-developers mailing list [email protected] http://lists.research.att.com/mailman/listinfo/ast-developers
