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Fix T92857: Deadlock in geometry nodes curve multi-threading 

The spline code, especially Bezier splines, often make use of lazily
evaluation and caching. In order to do that, they use mutex locks.
When multi-threading, this can lead to problems. Further detail
can be found in rBfcc844f8fbd0d1.

To fix the deadlock, isolate the task before multi-threading
when holding a lock.

Differential Revision: https://developer.blender.org/D13229
This commit is contained in:
Hans Goudey 2021-11-16 14:49:58 -06:00
parent cfd0e96e47
commit 25d30e6c99
Notes: blender-bot 2023-02-14 04:20:36 +01:00 
Referenced by issue #92857, Crash/deadlock with animation playback
1 changed files with 11 additions and 5 deletions
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16
source/blender/blenkernel/intern/spline_bezier.cc
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@ -599,7 +599,10 @@ Span<float> BezierSpline::evaluated_mappings() const
Span<int> offsets = this->control_point_offsets();
calculate_mappings_linear_resolution(offsets, size, resolution_, is_cyclic_, mappings);
blender::threading::isolate_task([&]() {
/* Isolate the task, since this is function is multi-threaded and holds a lock. */
calculate_mappings_linear_resolution(offsets, size, resolution_, is_cyclic_, mappings);
});
mapping_cache_dirty_ = false;
return mappings;
@ -635,10 +638,13 @@ Span<float3> BezierSpline::evaluated_positions() const
Span<int> offsets = this->control_point_offsets();
const int grain_size = std::max(512 / resolution_, 1);
blender::threading::parallel_for(IndexRange(size - 1), grain_size, [&](IndexRange range) {
for (const int i : range) {
this->evaluate_segment(i, i + 1, positions.slice(offsets[i], offsets[i + 1] - offsets[i]));
}
blender::threading::isolate_task([&]() {
/* Isolate the task, since this is function is multi-threaded and holds a lock. */
blender::threading::parallel_for(IndexRange(size - 1), grain_size, [&](IndexRange range) {
for (const int i : range) {
this->evaluate_segment(i, i + 1, positions.slice(offsets[i], offsets[i + 1] - offsets[i]));
}
});
});
if (is_cyclic_) {
this->evaluate_segment(