[development] including file-based caching in 4.7

[Jeremy Andrews]

Hello,

  Following the recent Drupal roadmap talks in Vancouver, I'd
like to propose the inclusion of file-based caching in Drupal
4.7. By making it possible to move cached data from the
database into the filesystem, the patch offers increased
reliability and performance.

  Find a patch against CVS HEAD with more details as to how
it works and some benchmarking results here:
  http://drupal.org/node/45414

  A quick summary from my most recent benchmarking, under a
heavy siege load:

  Database cache:
    1,000 pages in 34.1 seconds.  That's an average of 29.38
    pages per second, with each page loading in 34.12 ms.
    Under this load, 7.7% of the page requests failed.

  File cache:
    1,000 pages in 28.7 seconds.  That's an average of 36.1
    pages per second, with each page loading in 28.54 ms.  0
    page requests failed.

  File cache with FastPath:
    1,000 pages in 5.23 seconds.  That's an average of 191.12
    pages per second, with each page loading in 5.233 ms.  0
    page requests failed.

  (FastPath is a new bootstrap phase that allows the display
of file-cached pages for anonymous users without bootstraping
the database or sessions)

  Please feel free to test out the patch, running your own
benchmarks and making any suggestions.  Discussion as to
whether or not this should be included in 4.7 is also
encouraged.

Thanks,
 -Jeremy