Session Health Monitor helps keep SketchUp stable while you work.
IT IS A FREE EXTENSION FOR macOS ONLY
This is intended only to work on 2025 and 2026 SketchUp
It does two things:
1. Tracks SketchUp’s memory usage
-
Shows how much memory SketchUp is using (in MB).
-
Plots a simple trend line so you can see if memory is rising too fast.
-
Helps you spot early signs of instability or an upcoming crash.
-
Provides a pop-up to alert you when a specified memory jump has occurred, and suggest that you save or possibly restart.
This helps you decide when to save and restart SketchUp before it crashes. In a future version, it will include a report back on actual memory used as displayed in the activity monitor. Which demonstrates memory leakage. I use both session health monitor, and the OS activity monitor while modeling in SketchUp. Together, you will begin to see a pattern, then know when it’s time to jump ship and reboot.
Just look at this photo… 23GB for SU, yet it thinks its only using 600MB. Its kinda amazing it didn’t crash before this screenshot!
2. Cleans up SketchUp’s “crash leftovers”
SketchUp sometimes leaves behind autosave and recovery files after a crash.
These leftover files can cause:
-
“Recovered version is newer” warnings
-
Crashes when opening a model
-
Conflicts when SketchUp thinks you have a newer version that doesn’t exist
The extension adds a menu dropdown option:
Clean Session Garbage…
This safely moves SketchUp’s temporary autosave/recovery files into a quarantine folder so they stop causing problems.
The underlying problem on macOS + Cocoa (why SketchUp struggles)
SketchUp on macOS runs inside Apple’s Cocoa application framework.
While SketchUp works very well on Windows, the macOS version suffers from a long-standing issue:
1. SketchUp leaks memory through its Cocoa-based interfaces
SketchUp’s macOS user interface, dialogs, rendering views, and embedded Chromium panels (HtmlDialog) all allocate memory through Cocoa.
When these things are opened/closed repeatedly during long work sessions, some of that memory is never released.
Over time this creates steady memory growth even when:
-
the model isn’t growing
-
the geometry hasn’t changed
-
old data should have been freed
This is a memory leak at the Cocoa layer, not Ruby.
2. macOS memory pressure makes the problem worse
When SketchUp grows past about 10–15 GB of RAM:
-
macOS starts swapping memory into SSD storage
-
writes to files (autosave, temp files) can be interrupted
-
SketchUp’s internal autosave writes can become corrupted
-
temp recovery files are half-written
-
SketchUp loses track of which file is newest
This is exactly what causes those dialogs:
“A recovered version is newer than the file you are opening.”
Even when it’s wrong.
3. SketchUp never cleans up broken autosave/recovery data
After a memory-pressure crash, SketchUp leaves behind:
-
stale autosaves
-
half-written recovery files
-
metadata that claims a file is “newer” when it isn’t
These files are kept because SketchUp is very conservative about deleting anything that might contain user work.
But this leads to:
-
startup conflicts
-
models failing to open
-
SketchUp repeatedly offering “recovered” files that crash when opened
-
recovery loops
-
corrupted autosaves blocking real files
The user has to manually delete these folders to fix the problem — something most users never know to do.
Why Session Health Monitor helps on macOS specifically
A. It warns you before SketchUp becomes unstable
When SketchUp memory climbs too fast, it’s a sign Cocoa is leaking.
The extension lets you see the leak happening:
-
rising memory graph
-
increased MB usage
-
rapid 10-minute deltas
You know exactly when to save, restart, and avoid data loss.
B. It fixes the corrupted autosave/recovery problem
The extension adds the feature SketchUp is missing:
Clean Session Garbage
This safely moves only the broken autosave/recovery temp files that cause:
-
false “newer recovered version” warnings
-
startup crashes
-
dialogs that prevent loading the real model
-
SketchUp trying to open corrupted autosaves
It never touches .skp or ~.skp. In your project folder.
This solves the most common macOS-specific SketchUp crash loop.
C. It is a safe, controlled workaround for macOS/Cocoa limitations
Because SketchUp can’t easily rewrite its entire Cocoa memory and autosave layer, these leaks and leftover files have persisted for years.
This extension provides:
-
Memory awareness (so you can avoid the leak turning into a crash)
-
Garbage cleanup (so you can recover cleanly after a macOS-style crash)
If you’ve made it this far, here is the link to download this free extension.
SessionHealth_Merged_v1.2.0c.rbz (9.1 KB)
Do not use this if you are not comfortable with manually removing SketchUp extension/plug-ins. Yes, you install this like normal… but should it fail on your system, you should have a back up plan.
If this breaks your machine, it ain’t my fault.
Don’t talk to strangers… don’t take candy from weirdos.
There’s no free Wi-Fi in the van.
I’ll circle back and provide additional instruction on how to use the preferences and the CSV file that it creates to log memory events. When to use “Clean Session Garbage”, and where it’s quarantine folder is located, so you can recover or delete them.
I hope this is helpful for those like me who are doing some fairly complicated things… (with components being used as reference files. Multiple SU files open, lots and of scenes for multiple layout files.)
I anticipate that that SketchUp will soon retire/replace Cocoa, and this extension will have no purpose…
we can hope.
Nicholas