1 VEdit::render checking out
4 VEdit::draw checking out
6 VEdit::render checking in
7 ATrack::render checking out
13 VRender::process_buffer age video
17 but ATrack::render has locked check_out at this point.
18 VEdit::draw checking in
20 but Cache::age_type has locked check_in and check_out can't be unlocked until