RE: socket problem

[Tom Daly <Tdaly@xxxxxxxxxxxxxx>]

Scott,

Good ideas. I'm doing blocking reads.  The select has *null for the
write and error sets.  The timeout is 3 seconds.  When I do a WRKACTJOB
I see SELW status and high CPU%... it's the top running job on the
system!

I'll get the relevent code... sit tight.

Tom

-----Original Message-----
From: Scott Klement
To: 'rpg400-l@midrange.com'
Sent: 12/20/01 6:52 PM
Subject: RE: socket problem


Are these blocking or non-blocking sockets?

If they're non-blocking, is it possible that the select() is returning
immediately, even if theres no data to read?  This would cause it to
loop
from select() to read(), etc, taking up lots of CPU.

the most common cause I've seen for this is specifying a write or
exception descriptor set to select() in addition to a read, when that's
not really what the programmer meant to do.  Because a set of write
descriptors was given, and because there's still space in the write
buffer, select() always returns immediately.    Since you're only trying
to read from it, it loops and wastes CPU.

I'd recomment running the program in debug, and seeing exactly what
it's doing.   If it's truly stopping at the select() call, then it
shouldn't be using CPU, it should sit at "SELW" status.

If nothing else works, post the relevant section of code to this list,
and I'll see if a problem jumps out at me :)



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