$ docker pull python:3.6.4-stretch
3.6.4-stretch: Pulling from library/python
c73ab1c6897b: Pull complete
1ab373b3deae: Downloading [=============================================> ] 10.13MB/11.11MB
b542772b4177: Download complete
57c8de432dbe: Download complete
1ab373b3deae: Pull complete
b542772b4177: Pull complete
57c8de432dbe: Pull complete
1785850988c5: Pull complete
676ef2d8682b: Pull complete
56321bcc2d38: Pull complete
4788c366a216: Pull complete
0d970fbfeb26: Pull complete
Digest: sha256:db22cb78ba16cb6a0632eead1e48a239636a5a77c9f8cf343087acf309ad0248
Status: Downloaded newer image for python:3.6.4-stretch
Time: 0h:05m:33s
下载挂起的可能性高达上述输出的80％。然后保持此状态5分钟，并在重试开始时成功拉动。
有关更多详细信息，此问题在三个ubuntu pc中发生。 两种是Ubuntu 16.04，一种是18.04。所有机器都在同一办公网络上。
起初，我尝试更改docker和ubuntu版本，但失败了。 service docker restart也没用。我注意到我安装了新的千兆交换机集线器（https://iptime.com/iptime/?page_id=11&pf=12&page=2&pt=311&pd=1），并且怀疑集线器设备。当计算机不通过交换集线器直接连接到LAN时，它运行良好。当我将交换集线器更改为旧的100Mb / s时，它也运行良好。
可以认为这是千兆交换集线器的问题，但是很难找到答案，因为所有其他Internet使用都可以与千兆交换集线器一起很好地工作。所以我想知道docker pull是否没有其他问题，或者没有其他解决方案。
$ uname -a
Linux my-ubuntu18.04 4.15.0-42-generic #45-Ubuntu SMP Thu Nov 15 19:32:57 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
$ docker version
Client:
Version: 18.09.0
API version: 1.39
Go version: go1.10.4
Git commit: 4d60db4
Built: Wed Nov 7 00:48:57 2018
OS/Arch: linux/amd64
Experimental: false
Server: Docker Engine - Community
Engine:
Version: 18.09.0
API version: 1.39 (minimum version 1.12)
Go version: go1.10.4
Git commit: 4d60db4
Built: Wed Nov 7 00:16:44 2018
OS/Arch: linux/amd64
Experimental: false
请在我的docker daemon日志下面搜索failed关键字。
12:13:32 level=debug msg="Calling GET /_ping"
12:13:32 level=debug msg="Calling GET /v1.39/info"
12:13:32 level=debug msg="Calling POST /v1.39/images/create?fromImage=python&tag=3.6.6-stretch"
12:13:32 level=debug msg="Trying to pull python from https://registry-1.docker.io v2"
12:13:35 level=debug msg="Pulling ref from V2 registry: python:3.6.6-stretch"
12:13:35 level=debug msg="docker.io/library/python:3.6.6-stretch resolved to a manifestList object with 7 entries; looking for a unknown/amd64 match"
12:13:35 level=debug msg="found match for linux/amd64 with media type application/vnd.docker.distribution.manifest.v2+json, digest sha256:c306863aa2e858ccf00958c625ca2ffdbf8845da76e266b0b0d9c4760170aff3"
12:13:36 level=debug msg="Layer already exists: bc9ab73e5b14"
12:13:36 level=debug msg="Layer already exists: 193a6306c92a"
12:13:36 level=debug msg="Layer already exists: e5c3f8c317dc"
12:13:36 level=debug msg="Layer already exists: a587a86c9dcb"
12:13:36 level=debug msg="pulling blob \"sha256:72744d0a318b0788001cc4f5f83c6847ba4b753307fadd046b508bbc41eb9e29\""
12:13:36 level=debug msg="pulling blob \"sha256:6598fc9d11d10365ac9281071a87930a2382ee31d026f1b6d432717b31db387c\""
12:13:37 level=debug msg="Downloaded 6598fc9d11d1 to tempfile /var/lib/docker/tmp/GetImageBlob402585872"
12:13:37 level=debug msg="pulling blob \"sha256:4b1d9004d467b4e710d770a881df027df7e5e7e4629f6e473760893ffc1a667f\""
12:13:40 level=debug msg="Downloaded 72744d0a318b to tempfile /var/lib/docker/tmp/GetImageBlob083083061"
12:13:40 level=debug msg="pulling blob \"sha256:93612f47cdc374d0b33057b9e71eac173ac469da3e1a631dc8a32ba6986a408a\""
12:13:40 level=debug msg="Applying tar in /var/lib/docker/overlay2/9eaab31d9a1f108ba8a5c712cf23f36a9097140d09c76e6b966667fba2cc014b/diff" storage-driver=overlay2
12:13:42 level=debug msg="Downloaded 93612f47cdc3 to tempfile /var/lib/docker/tmp/GetImageBlob281534658"
12:13:42 level=debug msg="pulling blob \"sha256:1bc4b4b508703799ef67a807dacce4736045e642e87bcd49871cd0f23e7f5b8b\""
12:13:43 level=debug msg="Downloaded 1bc4b4b50870 to tempfile /var/lib/docker/tmp/GetImageBlob872144708"
12:13:48 level=debug msg="Applied tar sha256:9978d084fd771e0b3d1acd7f3525d1b25288ababe9ad8ed259b36101e4e3addd to 9eaab31d9a1f108ba8a5c712cf23f36a9097140d09c76e6b966667fba2cc014b, size: 556457027"
12:13:48 level=debug msg="Applying tar in /var/lib/docker/overlay2/3f91f78b3bb3f2cb6096472759bb84ae2f30f0825a7f935cad3b420c5cd71bee/diff" storage-driver=overlay2
12:13:48 level=debug msg="Applied tar sha256:2f4f74d3821ecbdd60b5d932452ea9e30cecf902334165c4a19837f6ee636377 to 3f91f78b3bb3f2cb6096472759bb84ae2f30f0825a7f935cad3b420c5cd71bee, size: 16849952"
12:18:46 level=error msg="Download failed, retrying: read tcp 10.251.12.218:48728->104.18.121.25:443: read: connection timed out"
12:18:51 level=debug msg="pulling blob \"sha256:4b1d9004d467b4e710d770a881df027df7e5e7e4629f6e473760893ffc1a667f\""
12:18:51 level=debug msg="attempting to resume download of \"sha256:4b1d9004d467b4e710d770a881df027df7e5e7e4629f6e473760893ffc1a667f\" from 20499209 bytes"
12:18:53 level=debug msg="Downloaded 4b1d9004d467 to tempfile /var/lib/docker/tmp/GetImageBlob954105135"
12:18:53 level=debug msg="Applying tar in /var/lib/docker/overlay2/458b54b72a80967b2ba5dfca870ed5de222677fc98910538674fbf15ce958dda/diff" storage-driver=overlay2
12:18:54 level=debug msg="Applied tar sha256:003bb6178bc3218242d73e51d5e9ab2f991dc607780194719c6bd4c8c412fe8c to 458b54b72a80967b2ba5dfca870ed5de222677fc98910538674fbf15ce958dda, size: 65191894"
12:18:54 level=debug msg="Applying tar in /var/lib/docker/overlay2/0f4a3bdc5aa6c4428d3368143b0b26c92dd19e12c7c536d20a95a3fdc8a221d3/diff" storage-driver=overlay2
12:18:54 level=debug msg="Applied tar sha256:15b32d849da2239b1af583f9381c7a75d7aceba12f5ddfffa7a059116cf05ab9 to 0f4a3bdc5aa6c4428d3368143b0b26c92dd19e12c7c536d20a95a3fdc8a221d3, size: 32"
12:18:54 level=debug msg="Applying tar in /var/lib/docker/overlay2/c7905eabea23cd147b6772ce255d536b0cdcb759d4387b8282259b338d392c34/diff" storage-driver=overlay2
12:18:54 level=debug msg="Applied tar sha256:6e5c5f6bf043bc634378b1e4b61af09be74741f2ac80204d7a373713b1fd5a40 to c7905eabea23cd147b6772ce255d536b0cdcb759d4387b8282259b338d392c34, size: 5918893"