Drastic drop in download speed after update to 3.1.1 on Synology NAS

[sladflob]

So I uninstalled Python3 and manually installed version 3.7.7.-14 from SynoCommunity and I'm back to full speed!

From a sabnzbd download:

Code: Select all

Downloaded in 11 mins 40 seconds at an average of 9.9 MB/s

And running the test script from Sander gives me:

Code: Select all

get_file_and_report_speed.py
No URL specificied, so using default
Start getting http://speed.transip.nl/100mb.bin
/tmp/tmplsg763wp 104857600 21.12897801399231
Speed in MB/s: 4.7

So this is good but not terribly satisfying. What's up with the Python3 update? How can I report this as a bug?

[sander]

So it's about python3 3.7.7.-14 versus 3.7.7.-15?

This python3 is built by a synology group. You could verify their changelog if you see anything.

If you report a bug with them, I would advice to once again upgrade to 3.7.7.-15 and see if you can still reproduce.

[sladflob]

That would appear to be the case. The release notes only say "update openssl to 1.1". I guess it could be a side-effect of that or maybe there are other changes that didn't make it into the notes.

And yes, I agree about upgrading to 3.7.7-15 to double check. It's painful, but I'll do it...

[sladflob]

OK verified. Updated to 3.7.7-15 and downloads went back to 2.2 MB/s. Downgraded and back to goodness again.

[sander]

OK verified. Updated to 3.7.7-15 and downloads went back to 2.2 MB/s. Downgraded and back to goodness again.

OK, 'good'. And that is download via SSL / NNTPS, right? If you use plain NNTP, is the speed low or high?

(Oh, wait: probably not relevant, as my test-script does plain HTTP not HTTPS, AFAIK)

[sladflob]

Yes, that is using SSL/NNTP.

Thanks so much for your help with this. I am just submitting an issue on github now.

[sladflob]

So it looks like it may indeed be SSL related. Disabling SSL with 3.7.7-15 restores downloads to full speed. I thought I had tested this case but I must be mistaken. And I'm sure the straight HTTP download was slower with 3.7.7-15...

From a comment on the github issue:

This is because this version of python from the SynoCommunity for the first time support openssl correctly.
So websites who support both http and https are now downloading via ssl encryption which cost performance

Hard to believe it's causing such a reduction in speed but maybe my NAS is a bit underpowered. But in that case wouldn't the CPU be working a lot harder?

I tried setting the cipher to AES128-SHA but it didn't make any difference. Any other ciphers I can try?

[sander]

(I changed to subject to match what you report.)

I'm not a fan of changing cipher.

I would try to report it somewhere on the synology forum, and stay on python 3.7.7-14 and hope that it gets solved in a future python-synology-release.