IO::Select->can_read() returns sockets with errors as well as sockets that are readable. My guess is that somewhere in there you have a read() or a sysread() or some other function that reads from the socket without testing for an error condition during that piece of code execution.
Here is a simple echo server that uses blocking IO and reports sockets that have errors.
#!/usr/bin/perl
use warnings;
use strict;
use IO::Socket;
use IO::Select;
use POSIX qw( BUFSIZ );
my $ALIVE = 1;
$SIG{ INT } = sub { warn "killed by interupt"; $ALIVE--; };
my $sock_group = IO::Select->new();
my $server = IO::Socket::INET->new(
Listen => 1,
LocalPort => 8080,
) or die $@;
$sock_group->add( $server );
while ( $ALIVE ) {
foreach my $sock ( $sock_group->can_read() ) {
if ( $sock == $server ) {
$sock_group->add( $server->accept() );
} else {
# first we try to read
my $buf;
my $rrv = sysread( $sock, $buf, BUFSIZ );
# if there is a read error
unless ( $rrv ) {
# we first report the error
if ( $rrv == 0 ) {
warn "$sock reached end of file";
} elsif ( not defined $rrv ) {
warn "$sock had error: $!";
} else {
warn "sock had an untrappable error";
}
# and then remove the socket from our set
$sock_group->remove( $sock );
$sock->close();
next;
}
# echo back what was said
my $wrv = syswrite( $sock, $buf );
unless ( $wrv == length( $buf ) ) {
if ( defined $wrv ) {
warn "incomplete write on $sock";
} else {
warn "write had error: $!";
}
$sock_group->remove( $sock );
$sock->close();
}
}
}
}
Hope that helps a bit,
-- Douglas Hunter | 