Supernode download docker image file very slow

[lixongyan]

When I docker pull from the client, I found some docker image layer file very slow to download. Then I checked supernode app.log, it looks like below:

2019-01-02 13:33:11.298  INFO 9 --- [pool-1-thread-9] c.a.d.supernode.service.cdn.Downloader   : taskId:535026d988f6d359fdba3b4542108dd1de321e99b614fd3a582b8dda3b614715 fileUrl:https://xxxx.xxxx.xxxx/v2/xxxx/my-image/blobs/sha256:5d4d42ff7708f88c2c36893b3f76d9e00f56090b24041efade1e30ad1d8479b1 on downloader
2019-01-02 13:36:21.283  INFO 9 --- [Thread-62] c.a.d.s.service.impl.CdnReporterImpl     : taskId:535026d988f6d359fdba3b4542108dd1de321e99b614fd3a582b8dda3b614715 fileLength:313942631 status:SUCCESS from:local
2019-01-02 13:36:21.284  INFO 9 --- [Thread-62] c.a.d.supernode.service.cdn.SuperWriter  : taskId:535026d988f6d359fdba3b4542108dd1de321e99b614fd3a582b8dda3b614715 readCost:188799,totalCost:189986,fileLength:313942256,realMd5:2d1108b5d071a22aa077d4fad9269973

we can see from the log, it takes around 190 seconds(total cost) to complete the requests, while the read cost is 188 seconds, could anyone kindly explain what is this read cost? Is it the time supernode downloading from registry? thanks!!!

[allencloud]

First of all, thanks sincerely for constantly using and supporting Dragonfly. We will try our best to keep Dragonfly better, and keep community and eco-system growing.

To get more feedback of Dragonfly's adoption in industry, would you mind helping comment in issue dragonflyoss/dragonfly#219 to give more information about your enterprise's Dragonfly usage. Thanks a lot in advance. @xiongyanLee

[haosdent]

@allencloud we encounter this when we testing dragonfly, do you have any ideas about this?

[lowzj]

This is limited by the downloading rate of supernode downloading from the registry site in the first time. If supernode has already holds the file, it will not download from registry again, the p2p network downloads from registry at most once.