add GIL ensure to startInterpreter

Author: lemei.huang

package.json

@@ -1,7 +1,7 @@
 {
   "name": "@fridgerator/pynode",
-  "version": "0.5.1",
-  "description": "Node <-> Python interopability",
+  "version": "0.5.2",
+  "description": "Node <-> Python interoperability",
   "main": "build/Release/PyNode",
   "author": "Nick Franken <shnick@gmail.com>",
   "license": "MIT",

src/pynode.cpp

@@ -19,7 +19,7 @@ Napi::Value StartInterpreter(const Napi::CallbackInfo &info) {
     mbstowcs(&path[0], pathString.c_str(), pathString.length());
     Py_SetPath(path.c_str());
   }
-  
+
   PyImport_AppendInittab("pynode", &PyInit_jswrapper);
 
   int isInitialized = Py_IsInitialized();
@@ -31,6 +31,9 @@ Napi::Value StartInterpreter(const Napi::CallbackInfo &info) {
   if (threadsInitialized == 0)
     PyEval_InitThreads();
 
+  /* Ensure GIL */
+  py_thread_context ctx;
+
   /* Load PyNode's own module into Python. This makes WrappedJSObject instances
      behave better (eg, having attributes) */
   PyObject *pName;
@@ -43,9 +46,6 @@ Napi::Value StartInterpreter(const Napi::CallbackInfo &info) {
         .ThrowAsJavaScriptException();
   }
 
-  /* Release the GIL. The other entry points back into Python re-acquire it */
-  PyEval_SaveThread();
-
   return env.Null();
 }
 

test.js

@@ -261,6 +261,12 @@ describe('nodePython', () => {
     })
   })
 
+  describe('duplicate startInterpreter', () => {
+      it('No error should happen when calling startInterpreter again', () => {
+          nodePython.startInterpreter();
+      });
+  })
+
   // describe('stopInterpreter', () => {
   //   it('should stop the interpreter', () => {
   //     nodePython.stopInterpreter()