c-ares / c-ares / #296

92%

Build Type

push

travis-ci

Committed by bradh352

Commit Message

Fix /etc/hosts processing performance with all entries using same IP address

Some users use blacklist files like https://github.com/StevenBlack/hosts which
can contain 200k+ host entries all pointing to 0.0.0.0.  Due to the merge
logic in the new hosts processor, all those entries will be associated as
aliases for the same ip address.

The first issue is that it attempts to check the status of all the hosts for
the merged entry, when it should only be checking the new hosts added to the
merged entry, so this caused exponential time as the entries got longer.

The next issue is if searching for one of those hosts, it would append all
the matches as cnames/aliases, but there is zero use for 200k aliases
being appended to a lookup, so we are artificially capping this to 100.

Bug report reference: https://bugs.gentoo.org/917400

Fix By: Brad House (@bradh352)

Run Details

13 of 15 new or added lines in 1 file covered. (86.67%)

5 existing lines in 1 file now uncovered.

7291 of 8787 relevant lines covered (82.97%)

1984.29 hits per line