2.78 crash on image datablock removal #49590

New Issue

notallowed · 2016-10-06T14:01:34+02:00

notallowed commented

2016-10-06 14:01:34 +02:00

System Information
Linux Mint 17.3, Nvidia GeForce GTX 760

Blender Version
Broken: 2.78.4bb1e22
Worked: 2.77a

Short description of error
Blender crashes when removing image datablock with Python API in attached blend file.
For easy testing attached blend file already has text "images_removal" which should remove all images, but crashes blender instead.

I also tried to use -d option and --factory-settings but still crashing. Moreover I even tried todays buildbot build: 2.78.3caa830 but still crashing.

However I did try to test this on different PC with Windows platform and released 2.78 version where crash did not appear.

Exact steps for others to reproduce the error

Open attached "truck.blend" file and load UI from it.
Navigate to Text Editor and run embedded "images_removal" script.
Crash.

truck.blend
truck.crash.txt

**System Information** Linux Mint 17.3, Nvidia GeForce GTX 760 **Blender Version** Broken: 2.78.4bb1e22 Worked: 2.77a **Short description of error** Blender crashes when removing image datablock with Python API in attached blend file. For easy testing attached blend file already has text "images_removal" which should remove all images, but crashes blender instead. I also tried to use -d option and --factory-settings but still crashing. Moreover I even tried todays buildbot build: 2.78.3caa830 but still crashing. However I did try to test this on different PC with Windows platform and released 2.78 version where crash did not appear. **Exact steps for others to reproduce the error** 1. Open attached "truck.blend" file and load UI from it. 2. Navigate to Text Editor and run embedded "images_removal" script. 3. Crash. [truck.blend](https://archive.blender.org/developer/F374617/truck.blend) [truck.crash.txt](https://archive.blender.org/developer/F374618/truck.crash.txt)

notallowed commented

2016-10-06 14:01:34 +02:00

Changed status to: 'Open'

notallowed commented

2016-10-06 14:01:34 +02:00

Added subscriber: @simon_lusenc

Sergey Sharybin commented

2016-10-06 14:21:03 +02:00

Added subscribers: @mont29, @Sergey

Bastien Montagne was assigned by Sergey Sharybin

2016-10-06 14:21:03 +02:00

Sergey Sharybin commented

2016-10-06 14:21:03 +02:00

@mont29, my guess would be the ID remap is involved here. Mind having a look? :)

Bastien Montagne commented

2016-10-06 14:55:09 +02:00

Changed status from 'Open' to: 'Archived'

Bastien Montagne closed this issue

2016-10-06 14:55:09 +02:00

Bastien Montagne commented

2016-10-06 14:55:09 +02:00

I kinda seriously doubt this ever worked, except by mistake/luck… You are blindly setting usercount of images to zero (user_clear()), and then delete them, whithout any care about potential actual users of those images.

You should not have to touch to image usercount anymore at all, just call bpy.data.images.remove(bpy.data.images- [x], do_unlink=True) is enough, do_unlink tells Blender to handle correctly all users of removed datablock.

No bug here, this clear_user() is actually a very bad (and dangerous, nice crash generator!) hack that used to be needed to work around our very weak handling of usercount in previous code, starting from 2.78 you should not need it anymore. Will add a note to releaselogs about it.

I kinda seriously doubt this ever worked, except by mistake/luck… You are blindly setting usercount of images to zero (`user_clear()`), and then delete them, whithout any care about potential actual users of those images. You should not have to touch to image usercount anymore at all, just call `bpy.data.images.remove(bpy.data.images- [x], do_unlink=True)` is enough, `do_unlink` tells Blender to handle correctly all users of removed datablock. No bug here, this `clear_user()` is actually a very bad (and dangerous, nice crash generator!) hack that used to be needed to work around our very weak handling of usercount in previous code, starting from 2.78 you should not need it anymore. Will add a note to releaselogs about it.

notallowed commented

2016-10-06 15:12:47 +02:00

@mont29 Well using new way of removal aka bpy.data.images.remove(bpy.data.images- [x], do_unlink=True) without "clear_user" doesn't help, blender still crashes. That's why I reported this, because no matter what I do I seem to not get around it on Linux.

EDIT: Now I even tried to remove all users via Shift + Click in UV Editor and then run the script only with "....remove(img, do_unlink=True)", still crashing. However in this case I got output to console:
ID user decrement error: IM4x2_bp.png (from '[Main]'): 0 <= 0
ID user count error: IM4x2_bp.png (from '[Main]')
ID user count error: IM4x2_bp.png (from '[Main]')

@mont29 Well using new way of removal aka bpy.data.images.remove(bpy.data.images- [x], do_unlink=True) without "clear_user" doesn't help, blender still crashes. That's why I reported this, because no matter what I do I seem to not get around it on Linux. EDIT: Now I even tried to remove all users via Shift + Click in UV Editor and then run the script only with "....remove(img, do_unlink=True)", still crashing. However in this case I got output to console: ID user decrement error: IM4x2_bp.png (from '[Main]'): 0 <= 0 ID user count error: IM4x2_bp.png (from '[Main]') ID user count error: IM4x2_bp.png (from '[Main]')

Bastien Montagne commented

2016-10-06 15:29:29 +02:00

Changed status from 'Archived' to: 'Open'

Bastien Montagne reopened this issue

2016-10-06 15:29:29 +02:00

Bastien Montagne commented

2016-10-06 15:29:29 +02:00

Eeeeh… OK, can confirm… please try to always report minimal case of bugs, the more you add to it, the more confusing it can be (and using clear_user to fix a crash is certainly not the way to go ;) )

Bastien Montagne commented

2016-10-06 18:03:00 +02:00

That .blend file is corrupted… 3DView's background pictures list is broken (last item does not have correct breaking NULL next pointer)…

Looks like I cannot reproduce this state from startup file, so afraid we need a way to reproduce this broken .blend file here.

That .blend file is corrupted… 3DView's background pictures list is broken (last item does not have correct breaking NULL next pointer)… Looks like I cannot reproduce this state from startup file, so afraid we need a way to reproduce this broken .blend file here.

notallowed commented

2016-10-07 10:58:50 +02:00

Well history of that file is quite long, I think that from blender version 2.74.
However I was able to recover SVN version of file that was still okay (executing above script didn't crash in 2.78), so hopefully it's not corrupted yet.

Now would it help if I would give you corrupted and non-corrupted files?

PS:
I am using unofficial addon on it, which uses pre_save handlers executing this:

    # clear unused materials, this has to be done because of usage of same material inside nodes
    for material in bpy.data.materials:
        if material.node_tree and material.users == 1:
            for node in material.node_tree.nodes:
                if node.type in ("MATERIAL_EXT", "MATERIAL"):
                    if node.material == material:
                        material.user_clear()

Might this be a source of problem, as user_clear is used again?

Well history of that file is quite long, I think that from blender version 2.74. However I was able to recover SVN version of file that was still okay (executing above script didn't crash in 2.78), so hopefully it's not corrupted yet. Now would it help if I would give you corrupted and non-corrupted files? PS: I am using unofficial addon on it, which uses pre_save handlers executing this: ``` # clear unused materials, this has to be done because of usage of same material inside nodes for material in bpy.data.materials: if material.node_tree and material.users == 1: for node in material.node_tree.nodes: if node.type in ("MATERIAL_EXT", "MATERIAL"): if node.material == material: material.user_clear() ``` Might this be a source of problem, as user_clear is used again?

Bastien Montagne commented

2016-10-07 11:45:08 +02:00

Well… what I need here is a way (steps) to reproduce corrupted file from sane one…

Don’t think that code can cause the issue, corruption is with the background pics list of the 3DView, so most likely some operation done at some point with those background images broke it (or, some versionning code between two releases of Blender went wrong, or, if you also opened and saved the file with some non-release builds, a transitional bug broke it, or…).

Typical case actually, a broken file is nearly never enough to understand the problem, without a way to reproduce it there are just too much possible causes to investigate them. :)

Well… what I need here is a way (steps) to reproduce corrupted file from sane one… Don’t think that code can cause the issue, corruption is with the background pics list of the 3DView, so most likely some operation done at some point with those background images broke it (or, some versionning code between two releases of Blender went wrong, or, if you also opened and saved the file with some non-release builds, a transitional bug broke it, or…). Typical case actually, a broken file is nearly never enough to understand the problem, without a way to reproduce it there are just too much possible causes to investigate them. :)

notallowed commented

2016-10-07 13:17:32 +02:00

Hm... it doesn't look good then, because I don't have exact steps :/

What I can tell is that between recovered SVN versions I was working with UV editor and changing vertex UVs. Also I was opening some images just for the period of changing UV layers. After I was done, I removed that images trough editor Shift + Click and re-saving the file. But I am sure that I wasn't working with background images at that time.

PS: Out of curiosity I tried to open latest corrupted blend file without loading UI and running that script does not crash blender anymore. So once opening that blend file without UI and saving file again should remove corruption problems? Is there any way I can check integrity of blend file?

Hm... it doesn't look good then, because I don't have exact steps :/ What I can tell is that between recovered SVN versions I was working with UV editor and changing vertex UVs. Also I was opening some images just for the period of changing UV layers. After I was done, I removed that images trough editor Shift + Click and re-saving the file. But I am sure that I wasn't working with background images at that time. PS: Out of curiosity I tried to open latest corrupted blend file without loading UI and running that script does not crash blender anymore. So once opening that blend file without UI and saving file again should remove corruption problems? Is there any way I can check integrity of blend file?

Bastien Montagne commented

2016-10-07 14:09:04 +02:00

Changed status from 'Open' to: 'Archived'

Bastien Montagne closed this issue

2016-10-07 14:09:04 +02:00

Bastien Montagne commented

2016-10-07 14:09:04 +02:00

Ah yes indeed, since broken stuff is in UI area, loading without UI shall fix the issue completely. :)

And no, no universal way to check a .blend file, aside from checking whether it crashes or not Blender xD

Will archive the report for now, we can always re-open it should you be able to reproduce the issue some day.

Ah yes indeed, since broken stuff is in UI area, loading without UI shall fix the issue completely. :) And no, no universal way to check a .blend file, aside from checking whether it crashes or not Blender xD Will archive the report for now, we can always re-open it should you be able to reproduce the issue some day.

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

2.78 crash on image datablock removal #49590