89f76f3cc6
Goroutine stack analisys shown some lock contention while doing massively (100 instances of `docker rm`) parallel image removal, with many goroutines waiting for the mountL mutex. Optimize it. With this commit, the above operation is about 3x faster, with no noticeable change to container creation times (tested on aufs and overlay2). kolyshkin@: - squashed commits - added description - protected CreateRWLayer against name collisions by temporary assiging nil to ls.mounts[name], and treating nil as "non-existent" in all the other functions. Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com> (cherry picked from commit 05250a4f0094e6802dd7d338d632ea632d0c7e34) Signed-off-by: Sebastiaan van Stijn <github@gone.nl> Upstream-commit: 78cbf4d1388a4eef155f08da0d2422e3a2cad11f Component: engine