statsCollector.publishers must be protected to prevent
modifications during the iteration in run().
Being locked for a long time is bad, so pairs of containers &
publishers (pointers) are copied to release the lock fast.
Signed-off-by: Anton Tiurin <noxiouz@yandex.ru>
Upstream-commit: 11a5f1af01842acf9a25ccebb59f36472ae51170
Component: engine