[OT] select and sysread problem on solaris

[Andy Wardley]

Paul Johnson wrote:
> Recently, another thirty or so pipes have been added to this group and
> very occassionally I am noticing a problem whereby select will indicate
> that a pipe is ready for reading and sysread will attempt to read from
> the pipe, but there is actually nothing there to be read, and so the
> sysread call hangs waiting for input.

Could it be a deferred signal?  See perldoc perlipc for more info.
 From some code I wrote:

     while (1) {
         $client = $server->accept() || do {
             # accept() can "fail" in Perl 5.7.3 and later thanks
             # to "safe signals" which can interrupt an accept()
             # so we detect this and ignore it
             next if $!{EINTR};
             last;
         };
         # handle $client request
     }

It's not using select(), but it could be a manifestation of the same
issue.

HTH
A