Why does "print" cause a Segmentation fault error in Apache2?

Question

The print method of Apache2::RequestIO constantly causes a Segamentation fault on my machine. I have a snippet readCookie.pm simple enough:

package readCookie;
use Apache2::Const -compile => 'OK';

sub handler{
    my $r = shift;
    $r->print("Hello!");
    return Apache2::Const::OK;
}
1;

But, after typing http://localhost/modPerl/readCookie, I got the the message below in my error.log

[Wed Aug 26 18:13:01.966600 2015] [core:notice] [pid 28200:tid 140520226109312] 
AH00052: child pid 28293 exit signal Segmentation fault (11)

and a webpage saying:

No data received
Details

clicking the Details, I got

Unable to load the webpage because the server sent no data.
Error code: ERR_EMPTY_RESPONSE

Can anybody tell me how to fix this? Anyone has successful experience using print method in Apache2.4.7 and Mod_Perl2.0.9?

Many thanks in advance!