How to kill your time by hardcoding?
Spend some time to make things configurable in start of a project to save hours of troubleshooting later in the project.
Tag function calling
Threads in Perl without using thread module
Perl threads are not good. If you need threads in Perl, try coding your multi-threaded part in C/C++, and wrap that in Perl.
Common coding pitfalls developers should avoid
If result of a function is needed more than once then don’t call that function multiple times. Save the result of that function in a variable and use that variable instead.