Comments on: NYTProf 4.04 – Came, Saw Ampersand, and Conquered

By: Peter (Stig) Edwards

Peter (Stig) Edwards — Tue, 05 Oct 2010 12:51:10 +0000

In additon to changes in perl, I was thinking of changes in hardware. I did try to create a simple benchmark to demonstrate a performance improvement, but was unable to observe a significant difference.

By: TimBunce

TimBunce — Sun, 03 Oct 2010 15:09:55 +0000

Some work has been done over the years to reduce the cost (see perldelta’s), but the definition of these variables requires a copy to be made. So there’s little that can be done to avoid that. You’re welcome to do some benchmarking.

By: Peter (Stig) Edwards

Peter (Stig) Edwards — Sun, 03 Oct 2010 13:48:17 +0000

I’m wondering if anyone reported a performance improvement after removing any of these variables.
I’m also wondering if anyone has simple demonstration code that shows the performance difference when benchmarked or profiled.
I don’t mean to sound ungrateful, just curious.
The WARNING in perlre has existed since 1997 (5.004), and much has changed since then.

By: Graham Knop

Graham Knop — Sat, 10 Jul 2010 06:43:19 +0000

Thanks for adding this. It will make it much easier to find these issues than the other modules available. After seeing the post about Devel::SawAmpersand and Devel::FindAmpersand, I tried to use them to check the WebGUI codebase for these issues. Unfortunately, the B::FindAmpersand module doesn’t work with a threaded perl, but B::Lint can do the same detection and did work.

I ended up finding uses of $& in CSS::Packer, HTML::Packer, and JavaScript::Packer, which now have bugs filed for the problem.