macOS 15.2: UMS constantly at 50% CPU

[umsuser]

I read saw similar threads, some quite old, some related to Java, but I saw no fix for this.

I disabled Thumbnail creation and also blocked any renderers that were deteced.

Still, UMS is constantly eating CPU time, it is the most active process on my Mac.

What is wrong here and what can I do to fix this?

Nothing is playing, the process should not do nothing.

[umsuser]

I read viewtopic.php?f=9&t=556 on how to create debug logs.

Let me expand on this, as the description does not fit reality, as it seems:

I needed to use the Hamburger menu in the upper right corner.

From there, Tools / View Logs and select "Pack debug files" here.
The button to create the zip file is named "Selected Zip files"


The resulting zip file is kind of broken, as the file name itself contains double quotes (as part of the name!):

$ ls | grep .zip
-rw-r--r--@ 1 user staff 222004 Feb 15 22:41 "ums_dbg_2025-02-15-22-41.zip"

I fixed the naming, but the name created by the webpage may prove to be difficult!

$ mv \"ums_dbg_2025-02-15-22-41.zip\" ums_dbg_2025-02-15-22-41.zip

[mik_s]

I don't see UMS doing anything in the logs. Was it showing high CPU usage when you made them?

Looking at the previous logs there was a lot of this.

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DEBUG 2025-02-14 00:43:12.977 [jupnp-sync-protocol 1128-1] Finishing configuration for UnknownRenderer
DEBUG 2025-02-14 00:43:12.978 [jupnp-sync-protocol 1128-1] Updating status button for UnknownRenderer
DEBUG 2025-02-14 00:43:12.979 [jupnp-sync-protocol 1128-1] Using default media renderer "UnknownRenderer"
INFO  2025-02-14 00:43:12.979 [jupnp-sync-protocol 1128-1] Media renderer was not recognized. Possible identifying HTTP headers:
User-Agent: Darwin/21.5.0, UPnP/1.1, MiniUPnPc/2.2.3

I don't have any more info as this would have been when TRACE mode was not enabled, just that this section is repeated a lot so may be the cause.
Do you have an idea what this device is? There was no IP in the logs to narrow this down.

Now that you mention it I think there is something wrong with the log name as when I create them it starts with a "_" like this "_ums_dbg_2025-02-16-01-39" and this may be the OS replacing the quotes (at least on win11).
I think those instructions need updating a bit to add how to do it from the WebUI as those are for the old GUI.

[umsuser]

Thanks for having a look into this.

I don't see UMS doing anything in the logs. Was it showing high CPU usage when you made them?

Yes, it always runs at around 40-50% CPU.

I noticed that I cannot STOP it with a SIGSTOP signal, which is also annoying.

I don't have any more info as this would have been when TRACE mode was not enabled, just that this section is repeated a lot so may be the cause.
Do you have an idea what this device is? There was no IP in the logs to narrow this down.

No.
UMS deteced my Macs and my Router as "Unknown Renderes" and I blocked all of them.
Only an iPad is not listed, but I don't stream anything and no streaming App is running on the iPad.

UMS does not seem to access the disk and only rarely the network, from what "Stats" says.
Still, it is burning CPU like no other - and cannot be stopped:

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PID    COMMAND      %CPU  TIME     #TH    #WQ  #PORT MEM    PURG   CMPRS  PGRP  PPID  STATE    BOOSTS               %CPU_ME %CPU_OTHRS
75209  UMS          42.3  07:11:33 103    3    482   557M   0B     143M   75209 1     stuck     0[55]               0.00000 0.00000

7 hours CPU time, and I restarted yesterday night.

If there is no cure, I need to stop the Application and then only start it when it is needed - which would be very inconvenient.

Now that you mention it I think there is something wrong with the log name as when I create them it starts with a "_" like this "_ums_dbg_2025-02-16-01-39" and this may be the OS replacing the quotes (at least on win11).
I think those instructions need updating a bit to add how to do it from the WebUI as those are for the old GUI.

That would be great, I was confused at first.

[umsuser]

I noticed something interesting:

Together with UMS, 2 other processes are always at the "top":

fskitd

UVFSService

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PID    COMMAND      %CPU  TIME     #TH    #WQ   #PORT MEM    PURG   CMPRS  PGRP  PPID  STATE    BOOSTS               %CPU_ME %CPU_OTHRS
84429  UMS          51.6  00:27.07 110    4     502   388M+  6944K  0B     84429 1     stuck     0[11]               0.00000 0.00000
435    fskitd       27.4  18:28:07 4/1    3/1   105   4385K  0B     1216K  435   1     running  *0[1]                12.6505 0.00000
730    UVFSService  17.3  12:12:04 2      1     39    91M    0B     13M    730   1     sleeping *0[1617723379+]      0.00000 12.65062

As soon as I stop UMS, those 2 processes also vanish from the top-CPU processes!

They keep running, but don't do anything anymore:

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$ ps auxwww | grep -E '(fskitd|UVFSService)'
root             68628   0.0  0.0 410924560   7728   ??  Ss   26Jan25   4:30.60 /System/Library/PrivateFrameworks/UVFSXPCService.framework/Versions/A/XPCServices/UVFSService.xpc/Contents/MacOS/UVFSService
root               730   0.0  0.5 411998752  81584   ??  Ss   10Jan25 732:20.72 /System/Library/PrivateFrameworks/UVFSXPCService.framework/Versions/A/XPCServices/UVFSService.xpc/Contents/MacOS/UVFSService
root               435   0.0  0.1 426970784  10528   ??  Ss   10Jan25 1108:32.21 /usr/libexec/fskitd

So, UMS is triggering them for "something".

Googling around, I found lots of people complaining about high CPU usage from those.

As it seems, fskit is involved in a framework that supports ExFAT filesystems, which is what my content for UMS is using!

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/dev/disk6s2 on /Volumes/MEDIA (exfat, local, nodev, nosuid, noowners, noatime, fskit)
/dev/disk5s2 on /Volumes/XTRMQ_MEDIA (exfat, local, nodev, nosuid, noowners, noatime, fskit)

But I have the file ".metadata_never_index" touched on this disk, so that Spotlight will not run on it.

Still, somehow UMS drags on this ... for some reason.

I now stopped UMS as I see no sign of relieve, even as I like it for streaming!

[mik_s]

UMS deteced my Macs and my Router as "Unknown Renderes" and I blocked all of them.
Only an iPad is not listed, but I don't stream anything and no streaming App is running on the iPad.

I wonder if this has anything to do with it as I noticed you had blocked several things and this may be blocking the normal traffic from the router.
As UMS has to talk to the router is is also ignoring the reply so sends the message again.
I'm not an expert with networking and know next to nothing about Macs so I guessing.

I looked into what that device could be and found that "Darwin/21.5.0" is something to do with safari so has to be one of your apple devices.
UMS detects the Windows media player on the computer it is running on so maybe this is the same thing but the renderer you blocked was its own.


The router should not show as a renderer as UMS filters non media devices like routers and hubs, unless it is running some service for this like network storage.
These devices should show only in network devices tab.

I actually tried to see what happens if I block my router and it kinda broke playback on my devices and caused windows defender to use 100% CPU for a short while.
I was also trying to build v15 alpha of UMS so don't know if that had any impact.
I spent the last hour or so trying to fix this but unblocking the router was not enough. I had to do a clean install of UMS.

Try allowing anything you blocked and if that does not work try a clean install of UMS.

[umsuser]

I only blocked things to get rid of the high CPU usage!

I can unblock all, but that does sure not fix the CPU issue.

The Router offers network shares, maybe because of this it is interpreted as rendering device?!?