Crash with paralell init and multiple Cryptomatte shaders in scene

[samhodge]

Please see:

https://gist.github.com/samhodge/86173d3797f3ad77fa60e93fd4990a94

crash is

`****

• Arnold 5.1.0.X linux clang-5.0.0 oiio-1.7.17 osl-1.9.0 vdb-4.0.0 clm-1.0.3.513 rlm-12.2.2 2018/05/XX XX:XX:XX 00:00:00 61MB | Cryptomatte manifest created - 0.000000 seconds 00:00:00 61MB | Cryptomatte manifest created - 0.000000 seconds
• CRASHED in AiArrayGetStrFunc at 00:00:00
• signal caught: SIGSEGV -- Invalid memory reference
• backtrace:
• 0 0x00007f961aea17e2 [libai.so ]
• 1 0x00000030f763265f [libc.so.6 ]

  2 0x00007f961a82135b [libai.so ] AiArrayGetStrFunc

• 3 0x00007f961a82135b [libai.so ] AiArrayGetStrFunc
• 4 0x00007f9604bfa998 [cryptomatte.so ] CryptomatteData::setup_all(AtString, AtString, AtString, AtArray, AtArray)
• 5 0x00007f9604bf6f23 [cryptomatte.so ] [cryptomatte_shader.cpp:0]
• 6 0x00007f961ae040bb [libai.so ]
• 7 0x00007f961ae0fc7b [libai.so ]
• 8 0x00007f961aea4d0d [libai.so ]
• 9 0x00000030f7e07aa0 [libpthread.so.0] [pthread_create.c :0]
• 10 0x00000030f76e8aac [libc.so.6 ] clone
• loaded modules:
• 0x00007f961a5b6000 libai.so
• 0x00000030f7600000 libc.so.6
• 0x00007f9604b62000 cryptomatte.so
• 0x00000030f7e00000 libpthread.so.0
• memory: VM 78323 MB, RSS 61 MB, 0 page faults

  ---

  Segmentation fault`

Will not happen everytime indicating it is a concurrency issue.

[jonahfriedman]

Thanks, I have reproduced the issue.

I notice that your scene contains multiple Cryptomatte shaders, and they are not being used as AOV shaders. If i get rid of them all except one, and plug it into only AOV shaders, it works. This isn't quite the intended use case - Is there a reason you're using it this way?

It probably is possible to fix the race condition.

[jonahfriedman]

Furthermore it's caused by having more than one Cryptomatte in the scene at all, which can happen by accident in a lot of ways, so it does need fixing.

[jonahfriedman]

This has been fixed and will be in the next release.