Anybody seen this.... upgraded to 3.7.1. Site worked fine for 36 hours and then this started. Massively poor response and timing out all the time. Trying all sorts of things but no conclusion yet.
Hoping for a miracle... as you do...
Can't say that I have considering 3.7 is barely out of 'omicron' phase. ;)
However, in a sandbox 3.7.1 see that in moodledata a 'lock' directory which is like moodledata/files ...
00 0f 14 1c 20 29 2e 32 3f 4c 69 6f 7d 8b a1 aa c3 c6 cc f9
06 12 17 1d 21 2d 31 3d 49 4e 6c 76 7f 9d a2 ba c5 ca e6 fe
Files are 0 byte:
00:
total 0
-rw-rw-rw-. 1 root apache 0 Jul 17 18:56 00f466af106e0caa5b26aff1ed671a85
06:
total 0
-rw-rw-rw-. 1 root apache 0 Jul 17 18:56 06b52ae74d3de3ab780a21ed088cafb0
contain no data ... am guessing if they exist it means lock to whatever is free or if exist date/time stamp or hash indicates status? Guess.
But ... experiment ...
manually removed all files in moodledata/lock/
Checked access functionality of 3.7.1 site (dashboard in your screen shot?) ... no errors ... and
the 0 byte bite files and directories were already re-created ... cron job?
Soooo .... ?????
'SoS', Ken
My suspicion is that the lock issue is a symptom, not a cause. However, given that I've got nothing else to go on, I'm off to experiment with that 
"manually removed all files in moodledata/lock/"
Hi Ken
I had the same problem and I tried your solution, it works with me
Thanks