Add a defensive comment about the TOCTOU race

1 files changed, 6 insertions, 0 deletions

diff --git a/tensorflow/python/lib/core/py_func.cc b/tensorflow/python/lib/core/py_func.cc
index 8c1fa31f05..a3c541da87 100644
--- a/tensorflow/python/lib/core/py_func.cc
+++ b/tensorflow/python/lib/core/py_func.cc
@@ -500,6 +500,12 @@ class PyFuncOp : public OpKernel {
       call.ins.push_back(ctx->input(i));
     }
 
+    // NOTE(mrry): There is a potential time-of-check-to-time-of-use race here.
+    // because it is possible that `Py_Finalize()` could be called in another
+    // thread between this check and the  call to `PyGILState_Ensure()`, which
+    // will abort the process if `Py_Finalize()` has been called. A more robust
+    // solution would be welcome, but it is not obvious how to make this work
+    // using the current Python C API.
     OP_REQUIRES(
         ctx, Py_IsInitialized(),
         errors::FailedPrecondition("Python interpreter state is not initialized. "