It seems that if the same input appears multiple times in the inputs argument of TF_SessionRun (from c_api.h) then the TF_SessionRun call never returns.
This issue can be reproduced by modifying c_api_test.cc and replacing the line:
csession.SetInputs({{feed, Int32Tensor(3)}});
With:
csession.SetInputs({{feed, Int32Tensor(3)}, {feed, Int32Tensor(3)}});
According to gdb, the process is waiting for a mutex in the RunState destructor from DirectSession.

What related GitHub issues or StackOverflow threads have you found by searching the web for your problem?

none

Environment info

Operating System: Linux 4.4

Installed version of CUDA and cuDNN: none

If installed from source, provide

1. The commit hash (git rev-parse HEAD)
   008bcae
2. The output of bazel version
   Build label: 0.3.1
   Build target: bazel-out/local-fastbuild/bin/src/main/java/com/google/devtools/build/lib/bazel/BazelServer_deploy.jar
   Build time: Fri Jul 29 09:09:52 2016 (1469783392)
   Build timestamp: 1469783392
   Build timestamp as int: 1469783392

If possible, provide a minimal reproducible example (We usually don't have time to read hundreds of lines of your code)

See above.

What other attempted solutions have you tried?

Logs or other output that would be helpful

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