The change in adaptive loader behaviour introduced in r3975:

The change in adaptive loader behaviour introduced in r3975:
now cache loader processes either as many files as specified by loader_files
or works no more than time specified by loader_threshold during each iteration.

loader_threshold was previously used to decrease loader_files or
to increase loader_timeout and this might eventually result in
downgrading loader_files to 1 and increasing loader_timeout to large values
causing loading cache for forever.