Hello Perl Monks !!

I came across a really unexpected issue while developing a code to read a netlist file containing just few lines. I have written down system details, the code and input file and finally I describe the problem at the end

System and Setup Info: Linux RHEL6 Perl Version 5.10.1

Code:

#!/usr/bin/perl
use strict;
use warnings;
use Switch;

#Common Variable Initialization
my %DeviceList = ();
my $netlist_file = "/home/abhishek_r/Tool_Development/Voltrace/Perl/ne
+tlist.scs";
my @InbuiltDeviceList = ('resistor','capacitor','inductor','vsource','
+isource');
my @subcktslist =       getSubcktList($netlist_file);
print @subcktslist;

TraceSubcktDevices($netlist_file);

sub getSubcktList{
    my $netlist = $_[0];
    my @subckts = ();
    open(READ_NETLIST, "<$netlist") or die "Couldn't open netlist file
+ for read, $!";

    while(<READ_NETLIST>){
        chomp;
        s/^\s+//;       #To remove leading blanks (if any) in the line
        #ignore line if it contains comments or initializing words for
+ spectre
        switch() {
            case /^[*\/]/i  {next;}
            case /simulator\s+lang/i {next;}
            case /^include/i {next;}
        }
        if(/subckt/i) {
            my $line = $_;
            my @words = split(/\s+/,$line); #Split the read line in $_
+ with white spaces as delimiter
            my $nameindex = 1;      #Default index where subckt name i
+s usally found
            if(/inline/i){          #To change name index if subckt de
+finition includes inline
                $nameindex = 2;
            }
            push @subckts,$words[$nameindex];
        }
    }
    close(READ_NETLIST);
    return @subckts;
}

sub TraceSubcktDevices{         #Input: (netlist_file, subcktname, key
+_init) where subcktname is the name of subckt that needs to be traced
+ in the netlist
    my $netlist = $_[0];
    my $subcktname = "hello";
    $subcktname =~ s/^\s*|\s*$//g;  #To remove all leading and trainin
+g blanks from input subckt name
    my $key_init = $_[2];
    my $skip=0;                     #Default Skip status for netlist l
+ine. 0 indicates "don't skip" and is set for TOPLEVEL
    if($subcktname){        #Set skip flag if input subckt name is not
+ blank i.e. the tracing is not required at TOPLEVEL
        $skip = 1;
    }
    open(READ_NETLIST, "<$netlist") or die "Couldn't open netlist file
+ for read, $!";
    while(<READ_NETLIST>){
        $skip = $skip + 1;
        print "Hello";
    }
    close(READ_NETLIST);
}
[download]

Input File: netlist.scs

// Generated for: spectre
// Generated on: Jul 26 15:10:24 2016
// Design library name: custom
// Design cell name: TOPLEVEL
// Design view name: schematic
simulator lang=spectre
global 0
//--------------------------------//
// Library name: custom
// Cell name: inv
// View name: schematic
subckt inv IN OUT VDD VSS
    M0 (OUT IN VSS VSS) nch l=60n w=200n m=1 nf=1 sd=200n ad=3.5e-14 \
        as=3.5e-14 pd=750n ps=750n nrd=0.5 nrs=0.5 sa=175n sb=175n sca
+=0 \
        scb=0 scc=0
    M2 (OUT IN VDD VDD) pch l=60n w=200n m=1 nf=1 sd=200n ad=3.5e-14 \
        as=3.5e-14 pd=750n ps=750n nrd=0.5 nrs=0.5 sa=175n sb=175n sca
+=0 \
        scb=0 scc=0
ends inv
// End of subcircuit definition.

// Library name: custom
// Cell name: BUF_DELAY
// View name: schematic
subckt BUF_DELAY IN OUT VDD VSS
    I1 (net11 OUT VDD VSS) inv
    I0 (IN net11 VDD VSS) inv
ends BUF_DELAY
// End of subcircuit definition.

// Library name: custom
// Cell name: INV_DELAY
// View name: schematic
subckt INV_DELAY IN OUT VDD VSS
    I2 (net08 OUT VDD VSS) inv
    I1 (net11 net08 VDD VSS) inv
    I0 (IN net11 VDD VSS) inv
ends INV_DELAY
// End of subcircuit definition.

// Library name: custom
// Cell name: TOPLEVEL
// View name: schematic
I2 (BUF_IN BUF_OUT VDD VSS) BUF_DELAY
I3 (INV_IN INV_OUT VDD VSS) INV_DELAY
I4 (INV_IN net8) isource type=pwl wave=[ 1u 1 2u 2 ]
V3 (VSS 0) vsource dc=0 type=dc
V2 (INV_IN 0) vsource dc=0 type=dc
V1 (BUF_IN 0) vsource dc=5 type=dc
V0 (VDD 0) vsource dc=5 type=dc
R0 (net8 VSS) rm1w l=10u w=2u mf=1
C0 (net8 0) capacitor c=1p

//----------------- Entering Netlist Footer -------------------//
[download]

The Problem: In the code, there are two subroutines getSubcktList() and TraceSubcktDevices(). The former subroutine works fine. The latter subroutine (i.e. TraceSubcktDevices()) is showing a very unexpected behavior. I have listed my observations below:

1) If the above code is run "as is" making sure that correct path of netlist.scs file is supplied at the beginning, the code gets stuck (I use Linux command line to run the code) with no response

2) If I swap the subroutines, i.e. define TraceSubcktDevices() first and getSubcktList(), the code works fine printing "Hello" as many times as the number of lines in input file netlist.scs

Can anyone please let me know why this is unexpected behavior being observed?

Thanks !!

Abhishek

update: edited/code tags by stevieb