In a Perl web app, "our" variable shared in different web request-responses?

Question

I'm writing a web app in Perl with Dancer. Suppose I declared an our variable $var in A.pm, and assign the content of file1 to it:

sub get_file_content {
    our $var = <FILE1>;
}

I declared var as our because I would like to use it later in another file B.pm:

sub display_file_content {
    &display($A::var);
} 

So, after get_file_content was executed, $var should be the content of file1. Before display_file_content is executed, I changed the content of file1, and clicked some button to execute display_file_content. As supposed, the original content of file1 was displayed.

Then I did the same thing as above, except that after changing the content of file1, I didn't click display_file_content button. Instead, I start another web request for the same page in another web browser. I executed get_file_content first, and click the button to go through display_file_content directly. The modified content of file1 was displayed in the second web browser. This is normal. However, when I click the display button in the first web browser, it also displayed the modified content, instead of the original one. As a comparison with the first experiment without the second web request in another web browser, it seems the variable $var is shared in both web request-response process. But why did it happen? Could you please give some explanations?

Answer 1

"It seems the variable var is shared in both request-response processes" because it is. The our keyword declares a package global. You're running your Dancer app in a persistent environment, your global variables are persistent also. You're going to need to reset any our variables at the beginning of each request.