Large session size in 1.12

[iamkaant@…]

The following bug report has been submitted:
Platform:        macOS-26.5-arm64-arm-64bit
ChimeraX Version: 1.12rc202605280043 (2026-05-28 00:43:25 UTC)
Description
I've opened a session created by ChimeraX 1.11 and containing 4053 entries in a ViewDock window. The file size was ~14MB. After doing some hitpicking I saved the session and its size grew to 2.5 GB. I'm attaching a json file with some stats I was able to retreive from the session file

Log:
UCSF ChimeraX version: 1.12rc202605280043 (2026-05-28)  
© 2016-2026 Regents of the University of California. All rights reserved.  
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OpenGL version: 4.1 Metal - 90.5
OpenGL renderer: Apple M5 Pro
OpenGL vendor: Apple

Python: 3.11.9
Locale: en_US.UTF-8
Qt version: PyQt6 6.10.2, Qt 6.10.0
Qt runtime version: 6.10.2
Qt platform: cocoa
Hardware:

    Hardware Overview:

      Model Name: MacBook Pro
      Model Identifier: Mac17,8
      Model Number: MGE44LL/A
      Chip: Apple M5 Pro
      Total Number of Cores: 18 (6 Super and 12 Performance)
      Memory: 24 GB
      System Firmware Version: 18000.120.36
      OS Loader Version: 18000.120.36

Software:

    System Software Overview:

      System Version: macOS 26.5 (25F71)
      Kernel Version: Darwin 25.5.0
      Time since boot: 9 days, 3 hours, 54 minutes

Graphics/Displays:

    Apple M5 Pro:

      Chipset Model: Apple M5 Pro
      Type: GPU
      Bus: Built-In
      Total Number of Cores: 20
      Vendor: Apple (0x106b)
      Metal Support: Metal 4
      Displays:
        LG HDR 4K:
          Resolution: 5120 x 2880 (5K/UHD+ - Ultra High Definition Plus)
          UI Looks like: 2560 x 1440 @ 60.00Hz
          Main Display: Yes
          Mirror: Off
          Online: Yes
          Rotation: Supported
        Color LCD:
          Display Type: Built-in Liquid Retina XDR Display
          Resolution: 3456 x 2234 Retina
          Mirror: Off
          Online: Yes
          Automatically Adjust Brightness: Yes
          Connection Type: Internal


Installed Packages:
    accessible-pygments: 0.0.5
    aiohappyeyeballs: 2.6.2
    aiohttp: 3.13.4
    aiosignal: 1.4.0
    alabaster: 1.0.0
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    bs4: 0.0.2
    build: 1.3.0
    certifi: 2025.7.14
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    ChimeraX-AddCharge: 1.5.20
    ChimeraX-AddH: 2.2.8
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    ChimeraX-AlignmentMatrices: 2.1
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    ChimeraX-Crystal: 1.0
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    ChimeraX-DistMonitor: 1.4.2
    ChimeraX-DockPrep: 1.2.1
    ChimeraX-Dssp: 2.0
    ChimeraX-EMDB-SFF: 1.0
    ChimeraX-ESMFold: 1.0
    ChimeraX-FileHistory: 1.0.1
    ChimeraX-FunctionKey: 1.0.1
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    ChimeraX-gltf: 1.0
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    ChimeraX-MutationScores: 1.0
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    ChimeraX-Nifti: 1.2
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    ChimeraX-ResidueFit: 1.0.1
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    ChimeraX-SeqView: 2.18
    ChimeraX-Shape: 1.1
    ChimeraX-Shell: 1.0.1
    ChimeraX-Shortcuts: 1.2.1
    ChimeraX-ShowSequences: 1.0.3
    ChimeraX-SideView: 1.0.1
    ChimeraX-SimilarStructures: 1.0.1
    ChimeraX-Smiles: 2.1.2
    ChimeraX-SmoothLines: 1.0
    ChimeraX-SNFG: 1.0
    ChimeraX-SpaceNavigator: 1.0
    ChimeraX-StdCommands: 1.19.3
    ChimeraX-STL: 1.0.1
    ChimeraX-Storm: 1.0
    ChimeraX-StructMeasure: 1.2.1
    ChimeraX-Struts: 1.0.1
    ChimeraX-Surface: 1.0.1
    ChimeraX-SwapAA: 2.0.1
    ChimeraX-SwapRes: 2.5.3
    ChimeraX-TapeMeasure: 1.0
    ChimeraX-TaskManager: 1.0
    ChimeraX-Test: 1.0
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    ChimeraX-ToolshedUtils: 1.2.4
    ChimeraX-Topography: 1.0
    ChimeraX-ToQuest: 1.0
    ChimeraX-Tug: 1.0.1
    ChimeraX-UI: 1.50.7
    ChimeraX-Umap: 1.0
    ChimeraX-uniprot: 2.3.2
    ChimeraX-UnitCell: 1.0.1
    ChimeraX-ViewDock: 1.6.2
    ChimeraX-VIPERdb: 1.0
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    ChimeraX-VolumeMenu: 1.0.1
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File attachment: cxs_metrics_report.json

cxs_metrics_report.json​

[iamkaant@…]

Added by email2trac

[Eric Pettersen]

Hi Andrii,

Is there any chance you could supply the original Mol2 file? I could then try saving a 1.11 session file and then re-saving in 1.12 and see if I get the same kind of bloating you're seeing...

--Eric

[iamkaant@…]

Hi Eric,

Thank you for looking into it! I failed to reproduce the issue. I think the difference may stem from the fact that the huge session appeared after the session in 1.12rc stayed opened for a day, and I did extensive hit picking + saved it several times. 

However, when I used 1.12rc to open a session saved in 1.11, and then saved a new copy, the list of ligands disappeared from the ViewDock window. The session still occupies 14M and the ligands are visible in the model panel, but ViewDock reports “0 compounds listed”.

The sessions are somewhat sensitive, so I’ll send them in a separate email.

Sincerely,
Andrii

[Eric Pettersen]

Hi Andrii,

Like you, so far I have been unable to reproduce the issue, with or without simulated hit picking. I will leave the session open on my desktop here at work and when I'm back in the office on Monday see how big a saved session is.

--Eric

[iamkaant@…]

Hi Eric,

I’ve experienced some instability with 1.12rc on M5 Pro/Tahoe 26.5, but nothing I've been able to reliably reproduce. In addition to session bloating and the disappearance of the ViewDock table, there was a case when my mouse wheel stopped working. I’m unsure about the possible source, as the laptop is new and MacOS was updated recently. These are probably just isolated glitches.

Also, the arrow keys now use the sorting order properly (#19804). Thank you so much!

 — Andrii

[Eric Pettersen]

The ChimeraX I left running with ViewDock over the weekend produces a normal sized session file, so I guess I don't know why it produced that gargantuan one for you that one time.

--Eric

[iamkaant@…]

Thank you for looking into it! My apologies for the confusion.

 — Andrii 

[Eric Pettersen]

Hi Andrii,

With the session file you sent separately I can *see* the problem, though I don't know how it happens. The problem is that each ligand has the scoring information (energy / desolvation / etc.) of _all_ ligands associated with it, rather than just its own scoring information. I don't know what triggers that behavior, but I will investigate.

--Eric