Blender Crashes when multiple Data Transfer modifiers are used #46672

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Gaia Clary · 2015-11-02T11:39:27+01:00

Gaia Clary commented

2015-11-02 11:39:27 +01:00

Blender Version
Broken: development version (after 2.76)

Short description of error

I have 3 objects A, B, C
data transfer modifier on A transfers data from B
data transfer modifier on C transfers data from B

When i move one of the objects around in object mode then occasionally Blender crashes.
I can reproduce this behavior when all addons are disabled.
And the problem goes away when i disable the data transfer modifiers.

Exact steps for others to reproduce the error

Open the included blend file data_transfer_normals.blend
select the middle object and move it around a bit.
what seems to work "best" is:

G z then move the mouse frantically on your desk.

Sometimes the crash happens right away, sometimes it takes minutes to get it to appear.

The crash takes longer to show up when blender is in debug mode,
but i can get it to break there within a minuite.
The crash happens always here:

  static void customData_update_offsets(CustomData *data)
  {
      const LayerTypeInfo *typeInfo;
      int i, offset = 0;

      for (i = 0; i < data->totlayer; ++i) {
          typeInfo = layerType_getInfo(data->layers[i].type);

          data->layers[i].offset = offset;
          offset += typeInfo->size;   /*<== Crash because typeinfo is NULL */
      }

      data->totsize = offset;
      CustomData_update_typemap(data);
  }

The reason for this is the last data layer (5) is not initialized or contains broken data.
Here is the content of data->layers- [x] when the crash happens:

data->layers[5]	{type=-33686019 offset=72 flag=-1414812757 ...}	CustomDataLayer
type	-33686019	int 
offset	72	int
flag	-1414812757	int
active	-1414812757	int
active_rnd	-1414812757	int
active_clone	-17891602	int
active_mask	-17891602	int
uid	-17891602	int
name	0x000000001f551330 ""	char[64]
data	0x0000000000000000	void *

The Main thread works on Object A (which has a data transfer modifier defined with source Object B)
The Stack of the Blender Main Thread is:

 blender-app.exe!customData_update_offsets(CustomData * data) Line 1619	C
 blender-app.exe!customData_add_layer__internal(CustomData * data, ...) Line 1925	C
 blender-app.exe!CustomData_add_layer(CustomData * data, int type, int alloctype, void * layerdata, int totelem) Line 1935	C
 blender-app.exe!dm_getLoopArray(DerivedMesh * dm) Line 155	C
 blender-app.exe!CDDM_calc_loop_normals_spacearr(DerivedMesh * dm, ...) Line 2620	C
 blender-app.exe!CDDM_calc_loop_normals(DerivedMesh * dm, ...) Line 2611	C
 blender-app.exe!data_transfer_dtdata_type_preprocess(Object * UNUSED_ob_src, ...) Line 279	C
 blender-app.exe!BKE_object_data_transfer_dm(Scene * scene, Object * ob_src, ...) Line 1171	C
 blender-app.exe!applyModifier(ModifierData * md, Object * ob, ...) Line 211	C
 blender-app.exe!modwrap_applyModifier(ModifierData * md, ...) Line 745	C
 blender-app.exe!mesh_calc_modifiers(Scene * scene, Object * ob, ...) Line 2037	C
 blender-app.exe!mesh_build_data(Scene * scene, Object * ob, ...) Line 2582	C
 blender-app.exe!makeDerivedMesh(Scene * scene, Object * ob, BMEditMesh * em, ...) Line 2676	C
 blender-app.exe!BKE_object_handle_data_update(EvaluationContext * eval_ctx, Scene * scene, ...) Line 203	C
 blender-app.exe!BKE_object_handle_update_ex(EvaluationContext * eval_ctx, Scene * scene, Object * ob, ...) Line 3144	C
 blender-app.exe!scene_update_object_func(TaskPool * pool, ...) Line 1471	C
 blender-app.exe!task_scheduler_thread_run(void * thread_p) Line 164	C

Besides this there is another concurrent thread that currently executes BKE_mesh_calc_normals_poly()
This thread works on object C (which has a data transfer modifier defined with source Object B)

The Stack of the concurrent Thread is:

blender-app.exe!BKE_mesh_calc_poly_normal(const MPoly * mpoly, ...) Line 1797
blender-app.exe!BKE_mesh_calc_normals_poly$omp$1() Line 242
blender-app.exe!BKE_mesh_calc_normals_poly(MVert * mverts, ...) Line 244
blender-app.exe!CDDM_calc_loop_normals_spacearr(DerivedMesh * dm, ...) Line 2652
blender-app.exe!CDDM_calc_loop_normals(DerivedMesh * dm, ...) Line 2611
blender-app.exe!data_transfer_dtdata_type_preprocess(Object * UNUSED_ob_src, ...) Line 279
blender-app.exe!BKE_object_data_transfer_dm(Scene * scene, Object * ob_src, ...) Line 1171
blender-app.exe!applyModifier(ModifierData * md, Object * ob, ...) Line 211
blender-app.exe!modwrap_applyModifier(ModifierData * md, ...) Line 745
blender-app.exe!mesh_calc_modifiers(Scene * scene, Object * ob, ...) Line 2037
blender-app.exe!mesh_build_data(Scene * scene, Object * ob, ...) Line 2582
blender-app.exe!makeDerivedMesh(Scene * scene, Object * ob, BMEditMesh * em, ...) Line 2676
blender-app.exe!BKE_object_handle_data_update(EvaluationContext * eval_ctx, ...) Line 203
blender-app.exe!BKE_object_handle_update_ex(EvaluationContext * eval_ctx, ...) Line 3144
blender-app.exe!scene_update_object_func(TaskPool * pool, ...) Line 1471
blender-app.exe!task_scheduler_thread_run(void * thread_p) Line 164

I hope this is enough to reproduce the issue.

**Blender Version** Broken: development version (after 2.76) **Short description of error** I have 3 objects A, B, C data transfer modifier on A transfers data from B data transfer modifier on C transfers data from B When i move one of the objects around in object mode then occasionally Blender crashes. I can reproduce this behavior when all addons are disabled. And the problem goes away when i disable the data transfer modifiers. **Exact steps for others to reproduce the error** Open the included blend file [data_transfer_normals.blend](https://archive.blender.org/developer/F249844/data_transfer_normals.blend) select the middle object and move it around a bit. what seems to work "best" is: G z then move the mouse frantically on your desk. Sometimes the crash happens right away, sometimes it takes minutes to get it to appear. The crash takes longer to show up when blender is in debug mode, but i can get it to break there within a minuite. The crash happens always here: ``` static void customData_update_offsets(CustomData *data) { const LayerTypeInfo *typeInfo; int i, offset = 0; ``` ``` for (i = 0; i < data->totlayer; ++i) { typeInfo = layerType_getInfo(data->layers[i].type); ``` ``` data->layers[i].offset = offset; offset += typeInfo->size; /*<== Crash because typeinfo is NULL */ } ``` ``` data->totsize = offset; CustomData_update_typemap(data); } ``` The reason for this is the last data layer (5) is not initialized or contains broken data. Here is the content of data->layers- [x] when the crash happens: ``` data->layers[5] {type=-33686019 offset=72 flag=-1414812757 ...} CustomDataLayer type -33686019 int offset 72 int flag -1414812757 int active -1414812757 int active_rnd -1414812757 int active_clone -17891602 int active_mask -17891602 int uid -17891602 int name 0x000000001f551330 "" char[64] data 0x0000000000000000 void * ``` The Main thread works on Object A (which has a data transfer modifier defined with source Object B) The Stack of the Blender Main Thread is: ``` blender-app.exe!customData_update_offsets(CustomData * data) Line 1619 C blender-app.exe!customData_add_layer__internal(CustomData * data, ...) Line 1925 C blender-app.exe!CustomData_add_layer(CustomData * data, int type, int alloctype, void * layerdata, int totelem) Line 1935 C blender-app.exe!dm_getLoopArray(DerivedMesh * dm) Line 155 C blender-app.exe!CDDM_calc_loop_normals_spacearr(DerivedMesh * dm, ...) Line 2620 C blender-app.exe!CDDM_calc_loop_normals(DerivedMesh * dm, ...) Line 2611 C blender-app.exe!data_transfer_dtdata_type_preprocess(Object * UNUSED_ob_src, ...) Line 279 C blender-app.exe!BKE_object_data_transfer_dm(Scene * scene, Object * ob_src, ...) Line 1171 C blender-app.exe!applyModifier(ModifierData * md, Object * ob, ...) Line 211 C blender-app.exe!modwrap_applyModifier(ModifierData * md, ...) Line 745 C blender-app.exe!mesh_calc_modifiers(Scene * scene, Object * ob, ...) Line 2037 C blender-app.exe!mesh_build_data(Scene * scene, Object * ob, ...) Line 2582 C blender-app.exe!makeDerivedMesh(Scene * scene, Object * ob, BMEditMesh * em, ...) Line 2676 C blender-app.exe!BKE_object_handle_data_update(EvaluationContext * eval_ctx, Scene * scene, ...) Line 203 C blender-app.exe!BKE_object_handle_update_ex(EvaluationContext * eval_ctx, Scene * scene, Object * ob, ...) Line 3144 C blender-app.exe!scene_update_object_func(TaskPool * pool, ...) Line 1471 C blender-app.exe!task_scheduler_thread_run(void * thread_p) Line 164 C ``` Besides this there is another concurrent thread that currently executes BKE_mesh_calc_normals_poly() This thread works on object C (which has a data transfer modifier defined with source Object B) The Stack of the concurrent Thread is: ``` blender-app.exe!BKE_mesh_calc_poly_normal(const MPoly * mpoly, ...) Line 1797 blender-app.exe!BKE_mesh_calc_normals_poly$omp$1() Line 242 blender-app.exe!BKE_mesh_calc_normals_poly(MVert * mverts, ...) Line 244 blender-app.exe!CDDM_calc_loop_normals_spacearr(DerivedMesh * dm, ...) Line 2652 blender-app.exe!CDDM_calc_loop_normals(DerivedMesh * dm, ...) Line 2611 blender-app.exe!data_transfer_dtdata_type_preprocess(Object * UNUSED_ob_src, ...) Line 279 blender-app.exe!BKE_object_data_transfer_dm(Scene * scene, Object * ob_src, ...) Line 1171 blender-app.exe!applyModifier(ModifierData * md, Object * ob, ...) Line 211 blender-app.exe!modwrap_applyModifier(ModifierData * md, ...) Line 745 blender-app.exe!mesh_calc_modifiers(Scene * scene, Object * ob, ...) Line 2037 blender-app.exe!mesh_build_data(Scene * scene, Object * ob, ...) Line 2582 blender-app.exe!makeDerivedMesh(Scene * scene, Object * ob, BMEditMesh * em, ...) Line 2676 blender-app.exe!BKE_object_handle_data_update(EvaluationContext * eval_ctx, ...) Line 203 blender-app.exe!BKE_object_handle_update_ex(EvaluationContext * eval_ctx, ...) Line 3144 blender-app.exe!scene_update_object_func(TaskPool * pool, ...) Line 1471 blender-app.exe!task_scheduler_thread_run(void * thread_p) Line 164 ``` I hope this is enough to reproduce the issue.

Gaia Clary commented

2015-11-02 11:39:27 +01:00

Changed status to: 'Open'

Bastien Montagne was assigned by Gaia Clary

2015-11-02 11:39:27 +01:00

Gaia Clary commented

2015-11-02 11:39:27 +01:00

Added subscriber: @GaiaClary

Gaia Clary commented

2015-11-02 11:41:58 +01:00

Added subscriber: @ideasman42

Campbell Barton commented

2015-11-02 13:52:19 +01:00

Seems 2+ modifiers will try to recalculate data on the source mesh at once.

https://developer.blender.org/diffusion/B/browse/master/source/blender/blenkernel/intern/data_transfer.c$277

Solutions could be...

Put a lock around calcLoopNormals call.
Have calcLoopNormals to take a data argument, so the data layers dm_src of aren't manipulated by multiple threads.

Seems 2+ modifiers will try to recalculate data on the source mesh at once. https://developer.blender.org/diffusion/B/browse/master/source/blender/blenkernel/intern/data_transfer.c$277 Solutions could be... - Put a lock around `calcLoopNormals` call. - Have `calcLoopNormals` to take a data argument, so the data layers `dm_src` of aren't manipulated by multiple threads.

Sergey Sharybin commented

2015-11-03 12:10:23 +01:00

Added subscriber: @Sergey

Bastien Montagne commented

2015-11-03 18:01:11 +01:00

Pfff… This actually ends up being a nice can of worms… :(

I spent some time this afternoon implementing idea we discussed with Campbell (making some kind of dm->getLoopNormals() which would take array of lnors as output arg, instead of modifying own CDlayers.

This is easy to add to DM, the problem here is data transfer code - it means we'll have to pass around poly_nors_src and loop_nors_src around in a bunch of functions, making even more complicated a piece of code that does not really need it. Even worse, it breaks the generic CDLayer interpolation system, which means we'd have to implement own handling for clnors, triple yuck. I’m really not inclined to keep going in that direction…

We could go to the quick and dirty solution (mutex lock for those DM functions that can modify internal CDlayers - I think we could have same kind of issues with even calcNormals() itself e.g., since it may create a vertex layer in case it's using orig mesh data...). But again finding all possible broken case will probably turn into can of you-know-what.

So, my idea currently would simply be to make a copy of source dm. That one would be local, so there should be no problem adding data layers to it… Not that nice for performances, but…

@ideasman42, @Sergey, what do you think?

Pfff… This actually ends up being a nice can of worms… :( I spent some time this afternoon implementing idea we discussed with Campbell (making some kind of `dm->getLoopNormals()` which would take array of lnors as output arg, instead of modifying own CDlayers. This is easy to add to DM, the problem here is data transfer code - it means we'll have to pass around `poly_nors_src` and `loop_nors_src` around in a bunch of functions, making even more complicated a piece of code that does not really need it. Even worse, it breaks the generic CDLayer interpolation system, which means we'd have to implement own handling for clnors, **triple yuck**. I’m really not inclined to keep going in that direction… We could go to the quick and dirty solution (mutex lock for those DM functions that can modify internal CDlayers - I think we could have same kind of issues with even `calcNormals()` itself e.g., since it may create a vertex layer in case it's using orig mesh data...). But again finding all possible broken case will probably turn into can of you-know-what. So, my idea currently would simply be to make a copy of source dm. That one would be local, so there should be no problem adding data layers to it… Not that nice for performances, but… @ideasman42, @Sergey, what do you think?

blender-admin commented

2015-11-03 21:16:58 +01:00

This issue was referenced by e43b6e2f97

This issue was referenced by e43b6e2f9725edd8cbe1ca8538c8a2bbdf1b45cd

Bastien Montagne commented

2015-11-03 21:21:08 +01:00

Changed status from 'Open' to: 'Resolved'

Bastien Montagne closed this issue

2015-11-03 21:21:08 +01:00

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Blender Crashes when multiple Data Transfer modifiers are used #46672