base: performance: operations slower in 2.7.x vs. 2.6.4: reclaim, rev-upgrade, clean

[mascguy (Christopher Nielsen)]

I've noticed that the three operations mentioned - reclaim, rev-upgrade, and clean - are noticeably slower with MacPorts 2.7.x vs. 2.6.4.

Per some discussion with Josh, we believe there haven't been any notable changes to these operations for the 2.7.x releases, so they should perform similarly to v2.6.4.

The standard disclaimer applies: As I'm running on an ancient 2008-era MacPro, I'm far more likely to notice things like this vs. 99% of our users. Nonetheless, if there is a performance regression - and it can be identified and resolved - it will be to everyone's benefit.

In terms of the approach: We'll enable TCL profiling, and generate results for each of the three operations (reclaim, rev-upgrade, clean), across both v2.6.4 and v2.7.1. To ensure we're comparing apples-to-apples, that will be done via a cloned VM, with an identical set of installed ports. The operations will also be run twice, with the first run done to prime the filesystem cache. The 2nd run will include profiling enabled.

This should be very straightforward: It's simply a matter of generating results, upgrading MacPorts, and repeating the process. Once done, I'll attach the various profiler outputs for analysis.

Thoughts/comments welcome, as always.