Description
After I run "docker service update" it took around 60 seconds for each task from "Ready" to "Running" in desired states. It was around 25-35 seconds with the same application version and on the same docker swarm cluster. What could cause this issue? (I believe it is rather the servers than the docker itself) but how can I trouble shooting this? And I could not see any documentation described what "Ready" means for desired states

Describe the results you received:

docker service ps service
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR
663dyntbzxdwixoauzqwpxmr7 service.1 myNexus:18444/app/service:0.0.150 server1 Ready Ready 59 seconds ago
alv8egzz7l3otbrukyp0w12up service.2 myNexus:18444/app/service:0.0.140 server2 Running Running 3 minutes ago

docker service ps service
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR
663dyntbzxdwixoauzqwpxmr7 service.1 myNexus:18444/app/service:0.0.150 server1 Running Running 1 seconds ago
alv8egzz7l3otbrukyp0w12up service.2 myNexus:18444/app/service:0.0.140 server2 Running Running 3 minutes ago

Describe the results you expected:

Additional information you deem important (e.g. issue happens only occasionally):
We used the same docker swarm master and 2 docker swarm workers. There are not much load on all these three servers and all with the same docker version and all servers are in the same sub network.

Output of docker version:
Docker version 1.12.3, build 6b644ec

Output of docker info:
Containers: 2
Running: 1
Paused: 0
Stopped: 1
Images: 29
Server Version: 1.12.3
Storage Driver: overlay
Backing Filesystem: xfs
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
Volume: local
Network: overlay host null bridge
Swarm: active
NodeID: 72gvia35ix61itfohl7k3u6rg
Is Manager: true
ClusterID: 7cwfx7po774vp8pfj40algdlb
Managers: 1
Nodes: 3
Orchestration:
Task History Retention Limit: 1
Raft:
Snapshot Interval: 10000
Heartbeat Tick: 1
Election Tick: 3
Dispatcher:
Heartbeat Period: 5 seconds
CA Configuration:
Expiry Duration: 3 months
Node Address: 10.14.57.32
Runtimes: runc
Default Runtime: runc
Security Options: seccomp
Kernel Version: 3.10.0-327.28.3.el7.x86_64
Operating System: CentOS Linux 7 (Core)
OSType: linux
Architecture: x86_64
CPUs: 2
Total Memory: 3.703 GiB
Name: master1
ID: NTMK:JGIK:ZDHP:37KK:LYTO:BJJV:6LIA:LVAC:S4GX:SGWX:LWTS:Z2MP
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): true
File Descriptors: 44
Goroutines: 141
System Time: 2016-11-11T09:33:07.023284896+01:00
EventsListeners: 0
Registry: https://index.docker.io/v1/
WARNING: bridge-nf-call-ip6tables is disabled
Insecure Registries:
127.0.0.0/8