D.Parrott@cs.ucl.ac.uk (Dave Parrott) (02/28/91)
I am prototyping a parallel processing system and have run in to a
problem ... I wonder if anyone can help?
I have a process called "subsystem" that listens to a fixed set of
named pipes (I'm using these for quickness at the moment). Up to a
fixed number of other processes all called "pe" can `log-in' to the
subsystem by registering on one of the currently unused input pipes;
the subsystem communicates back on the corresponding output pipe.
This works well for the 1st 5 pe's and then collapses on the 6th.
The susbsystem blocks trying to write to the pe to confirm that it is
now logged in and the pe blocks trying to read the message.
Using ps -gl I get the following:
F UID PID PPID CP PRI NI SZ RSS WCHAN STAT TT TIME COMMAND
4082011090 3688 3687 0 15 0 112 320 pause S p9 0:06 -csh (csh)
80211090 3714 3688 1 25 01576 8 T p9 0:33 emacs
4080011090 3850 3688 1 1 0 40 176 fifo_all I p9 0:00 subsystem
80011090 3851 3688 5 1 0 40 96 select I p9 0:00 pe
80011090 3852 3688 4 1 0 40 192 select I p9 0:00 pe
80011090 3853 3688 3 1 0 40 200 select I p9 0:00 pe
80011090 3854 3688 1 1 0 40 192 select I p9 0:00 pe
80011090 3855 3688 3 1 0 40 200 select I p9 0:00 pe
80011090 3856 3688 4 1 0 40 192 kernelma I p9 0:00 pe
11090 3860 3688 14 28 0 224 376 R p9 0:00 ps -gl
82011090 3718 3714 0 15 0 48 152 pause I pa 0:00 /usr/ucl/lib/
The pe's stopped in select are working correctly, the pe stopped in
kernalma... is not.
Any ideas???
I have confirmed that it is nothing to do with the named pipes
themselves or the number of i/o channels per process etc (the open()
calls work properly, it is the read() and write() calls that are
blocking).
thanks,
Dave.