Very Frequent Indexing, High Cpu And Battery Usage With V2.3 On Mac

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I've got what's admittedly a pretty large share, ~38GB, syncing between several Macs and a NAS.


2.3 has been great on the NAS and it works fine on the Macs except the thing is indexing several times an hour and chewing huge amounts of CPU and battery when it does.  CPU will peg a core at 100% for 15 minutes at a time and the Energy Impact on my laptops puts BitTorrent Sync as consuming about twice as much power as everything else running on those machines combined.


This was a complete non-issue with previous v2.x versions.


Is there anything I can provide to help debug?

[Here is a possible solution build - RomanZ]

Edited by RomanZ
Added link to possible solution
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Yes, you can write to support and submit debug logs from both peers. Also, please describe the share in more details - how many files are there, where they are physically located on each peer. When writing to support, please don't forget to mention this forum topic. 


So far you can increase rescan interval in Sync settings -> Advanced -> Power user. 

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I'm still seeing this with 2.3.1 even after a complete resync of all my data in a fresh folder unfortunately, will submit the logs.

Not sure if it's related but I noticed that the resync process from scratch was also VERY slow at times with transfers freezing for over 30 minutes at times despite the machines all sitting on the same LAN at the time.



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I am experiencing the same issues on OSX.

We have large amount of files (200 Gb divided in about 20 folders for a total of 300k files).

It's important to mention that the previous version with the same amount and type of data after the obvious CPU time needed during the startup phase, everything was calming down very quickly and running smooth.

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I’m also experiencing this problem on my systems.  I have a Windows 7 and Windows 10 system and they are both running BTSync slower.  With 2.2.7 after booting the system up or waking it from being a sleep the system would transfer the files almost immediately with no system lag.  With 2.3.1 – it takes about 10 min after waking the system for it to start transferring the files – and it uses a lot of CPU.

I ended up downgrading to 2.2.7 and the issues went away.

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Got this sorted, or at least worked around via support.

Under Options > Preferences > Advanced > Open power user preferences I was advised to set the folder_rescan_interval to 0, turning it off entirely.

Behaviour of BitTorrent Sync seems identical in my use case and the CPU usage is the best I've ever seen it.

That said, there's a definite increase in usage between 2.2.x and 2.3.x that's apparently being looked at.

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Some more discovered  causes are fixed. Download is available in this topic: 

Again, anyone, who 2.3.2 doesn't help, please write directly to support  and submit the logs from the affected machine to them, here's instruction to collect the logs. A few details about your setup - files' number and their physical location on the computer will be of use. Thank you! 

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  • 1 year later...

I also had high CPU utilization on two macOS machines, one being a MacBook 12" (2017) which was overwhelmed by Resilio Sync.

I am managing just two folders, but each has 1,654,405 files combined, over many sub-folders.  Sync was not transferring files despite the high CPU: all files were in a synced state.

It turns out that Sync was periodically re-scanning all of the files/folders every 10 minutes!  After disabling this, using the "power user preferences" option "folder_rescan_interval = 0", the high CPU usage disappeared completely on both machines.

Sync was still able to detect changes to each folder.  I suspect they are using the macOS FSEvents APIs where the OS tells Sync which files have changed without polling.

I would love to know why the folder_rescan_interval isn't set to 0 on macOS by default?  (And Windows, where I'm guessing the equivalent Windows Change Journals are being used?).

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