Syncrhonization of new folder takes forever

[esguti]

Expected behaviour

Download all the folder without checking synchronization status of each file.

Actual behaviour

When I select a subfolder (PERSONAL/Trabajo.bc) to synchronize. The Nextcloud client application, instead of downloading the folder, starts to check the synchronization of all the files, without displaying any progress bar. After several days, I stop the synchronization of the folder (tired of waiting).

Could it be that I have tried to synchronize the subfolder before and the DB register has not been deleted when I removed the folder from synchronization.

Steps to reproduce

1. Select a subfolder to syncrhonize (PERSONAL/Trabajo.bc in my case)
2. Apply the changes

Client configuration

Client version:

• Nextcloud version 2.5.2git
• Using Qt 5.5.1, built against Qt 5.5.1
• Using 'OpenSSL 1.0.2g 1 Mar 2016

Operating system:

• Linux Mint 18

Server configuration

Nextcloud version:

• 16.0.3

Logs

1. Client logfile:

• 20190912_0653_owncloud.log.0

2. Web server error log:

• no trace of error

3. Server logfile: nextcloud log (data/nextcloud.log):

• no trace of client interaction

[MagicFab]

I am experiencing the same with NextCloud client 2.5.3 on Ubuntu and Nextcloud server version 15 on Debian. This was supposed to be fixed since 2.5.x :( - see:
#208 Slow change detection with many files

Also see (mostly ignored):
#1165 linux desktop client slowness
#1390 NextCloud Desktop Client, always looks like it is syncing
#1133 Synchronization broken on Linux
#857 Upload or Download are really slow when changing network
#691 Sync performance slow for many files
#199 Client stuck in sync

In #1133 Someone indicates 2.5.0 works, I haven't tried it.
In #1165 Someone reports 2.3.3 works, but it also has outdated security libraires

[esguti]

I see several synchronization issues, but this problem in particular occurs when new files are downloaded for the first time. My point is, why the client makes http requests for checking synchronization if the file is not still on the client? The files are not modified, they don't even exist on client!

I will check further in the logs and the code.

[MagicFab]

It doesn't make sense. With 48365 files taking up 5.1GB, NC client indicates "5 days left" after an initial 3 HOUR check! I wish other applications had such problems on the same system and network, but they don't.

[esguti]

The issue is related with #691. The sync algorithm:

• Discover: discover every subfolder (DiscoverySingleDirectoryJob) and file
• Reconcile: for every file just confirm that is new
• Post-Reconcile: again for each file

I see no other possibility that changing the way the sync algorithm works for sync in a bunch or download in a bunch. Could serve same solution as #691 .