Moby: `docker inspect` and `docker info` blocks when removing a container lasts long

[tonicbupt]

When I use docker rm test-ci_web_rhExzB to remove a container, if this takes several seconds, docker inspect test-ci_web_rhExzB and docker info will block during the removal.
Output of docker version:

Client:
 Version:      1.11.0
 API version:  1.23
 Go version:   go1.5.4
 Git commit:   4dc5990
 Built:        Wed Apr 13 18:40:36 2016
 OS/Arch:      linux/amd64

Server:
 Version:      1.11.0
 API version:  1.23
 Go version:   go1.5.4
 Git commit:   4dc5990
 Built:        Wed Apr 13 18:40:36 2016
 OS/Arch:      linux/amd64

Output of docker info:

Client:
 Version:      1.11.0
 API version:  1.23
 Go version:   go1.5.4
 Git commit:   4dc5990
 Built:        Wed Apr 13 18:40:36 2016
 OS/Arch:      linux/amd64

Server:
 Version:      1.11.0
 API version:  1.23
 Go version:   go1.5.4
 Git commit:   4dc5990
 Built:        Wed Apr 13 18:40:36 2016
 OS/Arch:      linux/amd64
[root@zzz1 ~]# docker info
Containers: 7
 Running: 7
 Paused: 0
 Stopped: 0
Images: 71
Server Version: 1.11.0
Storage Driver: devicemapper
 Pool Name: docker-253:1-170723-pool
 Pool Blocksize: 65.54 kB
 Base Device Size: 10.74 GB
 Backing Filesystem: xfs
 Data file: /dev/loop0
 Metadata file: /dev/loop1
 Data Space Used: 2.112 GB
 Data Space Total: 107.4 GB
 Data Space Available: 14.67 GB
 Metadata Space Used: 6.103 MB
 Metadata Space Total: 2.147 GB
 Metadata Space Available: 2.141 GB
 Udev Sync Supported: true
 Deferred Removal Enabled: false
 Deferred Deletion Enabled: false
 Deferred Deleted Device Count: 0
 Data loop file: /var/lib/docker/devicemapper/devicemapper/data
 WARNING: Usage of loopback devices is strongly discouraged for production use. Either use `--storage-opt dm.thinpooldev` or use `--storage-opt dm.no_warn_on_loop_devices=true` to suppress this warning.
 Metadata loop file: /var/lib/docker/devicemapper/devicemapper/metadata
 Library Version: 1.02.107-RHEL7 (2015-12-01)
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: calico bridge null host
Kernel Version: 3.10.0-123.4.4.el7.x86_64
Operating System: CentOS Linux 7 (Core)
OSType: linux
Architecture: x86_64
CPUs: 1
Total Memory: 994.1 MiB
Name: zzz1
ID: SZOF:P2GX:U5LA:F77I:Q4NK:JC2H:O55Y:64A6:SVFA:SZVY:XN3S:4IUQ
Docker Root Dir: /var/lib/docker
Debug mode (client): false
Debug mode (server): false
Registry: https://index.docker.io/v1/
WARNING: bridge-nf-call-ip6tables is disabled
Cluster store: etcd://10.10.192.213:2379

Steps to reproduce the issue:

1. create a container
2. stop and remove it
3. during the removal in another terminal, type docker info, here blocks

I understand the blocking of docker inspect, but why will docker info also block? It just collect some information about the server and output...

[cpuguy83]

Because it of the running/paused/stopped breakdown in the info struct.