Cycles standalone randomly crashing on Mojave and Catalina but not on Sierra. #74415

New Issue

Giovanni Remigi · 2020-03-04T01:19:44+01:00

Giovanni Remigi commented

2020-03-04 01:19:44 +01:00

I've been using Cycles as a library inside my own project for years, building it on Windows (MinGW64), Linux (gcc) and macOS Sierra (clang) without any issue. I've recently migrated to Mojave and updated all Cycles code to the very last commit the end of February 2020. On Sierra, after the update, it still compiles and works perfectly as ever, but on Mojave and Catalina it crashes randomly. On Windows and Linux it runs perfectly.

Initially, I blamed the new version of Xcode, but if I compile on Sierra (with the latest code of cycles) and then move the application to Mojave, I still experience random crashes.

It seems the crash appears when I create and destroy a session (either working in background or directly on screen) multiple times. I spent one month to dig up the problem and I found one single line of code which causes the random crash, the line which creates the array data1 in the file bvh.cpp, see snippet below.

        /* Modify offsets into arrays */
        int4 data = bvh_nodes[i + nsize_bbox];
        int4 data1 = bvh_nodes[i + nsize_bbox - 1]; <-- this is the line
        if (use_obvh) {
          data.z += (data.z < 0) ? -noffset_leaf : noffset;
          data.w += (data.w < 0) ? -noffset_leaf : noffset;
          data.x += (data.x < 0) ? -noffset_leaf : noffset;
          data.y += (data.y < 0) ? -noffset_leaf : noffset;
          data1.z += (data1.z < 0) ? -noffset_leaf : noffset;
          data1.w += (data1.w < 0) ? -noffset_leaf : noffset;
          data1.x += (data1.x < 0) ? -noffset_leaf : noffset;
          data1.y += (data1.y < 0) ? -noffset_leaf : noffset;
        }
        else {
          data.z += (data.z < 0) ? -noffset_leaf : noffset;
          data.w += (data.w < 0) ? -noffset_leaf : noffset;
          if (use_qbvh) {
            data.x += (data.x < 0) ? -noffset_leaf : noffset;
            data.y += (data.y < 0) ? -noffset_leaf : noffset;
          }
        }
        pack_nodes[pack_nodes_offset + nsize_bbox] = data;
        if (use_obvh) {
          pack_nodes[pack_nodes_offset + nsize_bbox - 1] = data1;
        }

I fixed the issue by moving the line which creates the array data1 into the if condition as following.

        /* Modify offsets into arrays */
        int4 data = bvh_nodes[i + nsize_bbox];
        if (use_obvh) {
          int4 data1 = bvh_nodes[i + nsize_bbox - 1];
          data.z += (data.z < 0) ? -noffset_leaf : noffset;
          data.w += (data.w < 0) ? -noffset_leaf : noffset;
          data.x += (data.x < 0) ? -noffset_leaf : noffset;
          data.y += (data.y < 0) ? -noffset_leaf : noffset;
          data1.z += (data1.z < 0) ? -noffset_leaf : noffset;
          data1.w += (data1.w < 0) ? -noffset_leaf : noffset;
          data1.x += (data1.x < 0) ? -noffset_leaf : noffset;
          data1.y += (data1.y < 0) ? -noffset_leaf : noffset;
          pack_nodes[pack_nodes_offset + nsize_bbox] = data;
          pack_nodes[pack_nodes_offset + nsize_bbox - 1] = data1;
        }
        else {
          data.z += (data.z < 0) ? -noffset_leaf : noffset;
          data.w += (data.w < 0) ? -noffset_leaf : noffset;
          if (use_qbvh) {
            data.x += (data.x < 0) ? -noffset_leaf : noffset;
            data.y += (data.y < 0) ? -noffset_leaf : noffset;
          }
          pack_nodes[pack_nodes_offset + nsize_bbox] = data;
        }

The code of both snippets does exactly the same thing, there is no functional change. The only difference is that data1 is created only when it is used. If I used a layout BH2, data1 is not required but it is created anyway.

I cannot really explain why the random crash happens on Mojave and Catalina only, I think it is due to some concurrency issue while sessions are created and destroyed one after the other in close sequence. Considering that both snippets of code are equivalent and that the new code avoid the creation of the array data1 when not required, the change seems to me a reasonable one with a small gain in performance when using a BH2 layout. It definitely fixes the random crash I've experienced on macOS Mojave and Catalina.

Regards,

Giovanni

I've been using Cycles as a library inside my own project for years, building it on Windows (MinGW64), Linux (gcc) and macOS Sierra (clang) without any issue. I've recently migrated to Mojave and updated all Cycles code to the very last commit the end of February 2020. On Sierra, after the update, it still compiles and works perfectly as ever, but on Mojave and Catalina it crashes randomly. On Windows and Linux it runs perfectly. Initially, I blamed the new version of Xcode, but if I compile on Sierra (with the latest code of cycles) and then move the application to Mojave, I still experience random crashes. It seems the crash appears when I create and destroy a session (either working in background or directly on screen) multiple times. I spent one month to dig up the problem and I found one single line of code which causes the random crash, the line which creates the array data1 in the file bvh.cpp, see snippet below. ``` /* Modify offsets into arrays */ int4 data = bvh_nodes[i + nsize_bbox]; int4 data1 = bvh_nodes[i + nsize_bbox - 1]; <-- this is the line if (use_obvh) { data.z += (data.z < 0) ? -noffset_leaf : noffset; data.w += (data.w < 0) ? -noffset_leaf : noffset; data.x += (data.x < 0) ? -noffset_leaf : noffset; data.y += (data.y < 0) ? -noffset_leaf : noffset; data1.z += (data1.z < 0) ? -noffset_leaf : noffset; data1.w += (data1.w < 0) ? -noffset_leaf : noffset; data1.x += (data1.x < 0) ? -noffset_leaf : noffset; data1.y += (data1.y < 0) ? -noffset_leaf : noffset; } else { data.z += (data.z < 0) ? -noffset_leaf : noffset; data.w += (data.w < 0) ? -noffset_leaf : noffset; if (use_qbvh) { data.x += (data.x < 0) ? -noffset_leaf : noffset; data.y += (data.y < 0) ? -noffset_leaf : noffset; } } pack_nodes[pack_nodes_offset + nsize_bbox] = data; if (use_obvh) { pack_nodes[pack_nodes_offset + nsize_bbox - 1] = data1; } ``` I fixed the issue by moving the line which creates the array data1 into the if condition as following. ``` /* Modify offsets into arrays */ int4 data = bvh_nodes[i + nsize_bbox]; if (use_obvh) { int4 data1 = bvh_nodes[i + nsize_bbox - 1]; data.z += (data.z < 0) ? -noffset_leaf : noffset; data.w += (data.w < 0) ? -noffset_leaf : noffset; data.x += (data.x < 0) ? -noffset_leaf : noffset; data.y += (data.y < 0) ? -noffset_leaf : noffset; data1.z += (data1.z < 0) ? -noffset_leaf : noffset; data1.w += (data1.w < 0) ? -noffset_leaf : noffset; data1.x += (data1.x < 0) ? -noffset_leaf : noffset; data1.y += (data1.y < 0) ? -noffset_leaf : noffset; pack_nodes[pack_nodes_offset + nsize_bbox] = data; pack_nodes[pack_nodes_offset + nsize_bbox - 1] = data1; } else { data.z += (data.z < 0) ? -noffset_leaf : noffset; data.w += (data.w < 0) ? -noffset_leaf : noffset; if (use_qbvh) { data.x += (data.x < 0) ? -noffset_leaf : noffset; data.y += (data.y < 0) ? -noffset_leaf : noffset; } pack_nodes[pack_nodes_offset + nsize_bbox] = data; } ``` The code of both snippets does exactly the same thing, there is no functional change. The only difference is that data1 is created only when it is used. If I used a layout BH2, data1 is not required but it is created anyway. I cannot really explain why the random crash happens on Mojave and Catalina only, I think it is due to some concurrency issue while sessions are created and destroyed one after the other in close sequence. Considering that both snippets of code are equivalent and that the new code avoid the creation of the array data1 when not required, the change seems to me a reasonable one with a small gain in performance when using a BH2 layout. It definitely fixes the random crash I've experienced on macOS Mojave and Catalina. Regards, Giovanni

Giovanni Remigi commented

2020-03-04 01:19:44 +01:00

Added subscriber: @GiovanniRemigi

Jacques Lucke commented

2020-03-04 10:44:07 +01:00

Added subscriber: @JacquesLucke

Jacques Lucke commented

2020-03-04 10:44:07 +01:00

Changed status from 'Needs Triage' to: 'Archived'

Jacques Lucke closed this issue

2020-03-04 10:44:07 +01:00

Jacques Lucke self-assigned this 2020-03-04 10:44:07 +01:00

Jacques Lucke commented

2020-03-04 10:44:07 +01:00

Can you upload this as a patch, please? Then it can go through normal code review.

I'll close this as invalid, because this should be a patch.

Thanks for the contribution.

Can you upload this as a patch, please? Then it can go through normal code review. I'll close this as invalid, because this should be a patch. Thanks for the contribution.

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Cycles standalone randomly crashing on Mojave and Catalina but not on Sierra. #74415