Use async_start_new_kernel_client from nbclient

share/jupyter/voila/templates/lab/index.html.j2

@@ -46,7 +46,7 @@ var voila_process = function(cell_index, cell_count) {
     Therefore it is important to have the cell loop in the template.
     The issue for Jinja is: https://github.com/pallets/jinja/issues/1044
     #}
-    {%- for cell in cell_generator(nb, kernel_id) -%}
+    {%- for cell in cell_generator(nb) -%}
       {% set cellloop = loop %}
       {%- block any_cell scoped -%}
       <script>

tests/app/conftest.py

@@ -19,7 +19,7 @@ def voila_config():
 
 @pytest.fixture
 def voila_args_extra():
-    return []
+    return ['--VoilaExecutor.timeout=240']
 
 
 @pytest.fixture

tests/app/execute_cpp_test.py

@@ -11,7 +11,7 @@ def cpp_file_url(base_url):
 
 @pytest.fixture
 def voila_args_extra():
-    return ['--VoilaConfiguration.extension_language_mapping={".xcpp": "C++11"}']
+    return ['--VoilaConfiguration.extension_language_mapping={".xcpp": "C++11"}', '--VoilaExecutor.timeout=240']
 
 
 @pytest.fixture

tests/app/many_iopub_messages_test.py

@@ -5,7 +5,7 @@
 
 @pytest.fixture
 def voila_args_extra():
-    return ['--ExecutePreprocessor.timeout=180']
+    return ['--VoilaExecutor.timeout=180']
 
 
 @pytest.fixture

tests/app/no_strip_sources_test.py

@@ -8,7 +8,7 @@
 
 @pytest.fixture
 def voila_args_extra():
-    return ['--VoilaConfiguration.strip_sources=False']
+    return ['--VoilaConfiguration.strip_sources=False', '--VoilaExecutor.timeout=240']
 
 
 async def test_no_strip_sources(http_server_client, base_url):

tests/app/template_arg_test.py

@@ -4,7 +4,7 @@
 
 @pytest.fixture
 def voila_args_extra():
-    return ['--template=test_template']
+    return ['--template=test_template', '--VoilaExecutor.timeout=240']
 
 
 async def test_template(http_server_client, base_url):

tests/app/template_cli_test.py

@@ -10,7 +10,7 @@
 def voila_args_extra():
     path_test_template = os.path.abspath(os.path.join(BASE_DIR, '../test_template/share/jupyter/voila/templates/test_template/'))
     path_default = os.path.abspath(os.path.join(BASE_DIR, '../../share/jupyter/voila/templates/default'))
-    return ['--template=None', '--VoilaTest.template_paths=[%r, %r]' % (path_test_template, path_default)]
+    return ['--template=None', '--VoilaTest.template_paths=[%r, %r]' % (path_test_template, path_default), '--VoilaExecutor.timeout=240']
 
 
 async def test_template_test(http_server_client, base_url):

tests/app/template_config_file_test.py

@@ -10,7 +10,7 @@
 def voila_args_extra():
     path_test_template = os.path.abspath(os.path.join(BASE_DIR, '../test_template/share/jupyter/voila/templates/test_template/nbconvert_templates'))
     path_default = os.path.abspath(os.path.join(BASE_DIR, '../../share/jupyter/voila/templates/default/nbconvert_templates'))
-    return ['--template=test_template', '--Voila.nbconvert_template_paths=[%r, %r]' % (path_test_template, path_default)]
+    return ['--template=test_template', '--Voila.nbconvert_template_paths=[%r, %r]' % (path_test_template, path_default), '--VoilaExecutor.timeout=240']
 
 
 async def test_template_test(http_server_client, base_url):

tests/app/template_custom_test.py

@@ -8,7 +8,7 @@
 
 @pytest.fixture
 def voila_args_extra():
-    return ['--template=None']
+    return ['--template=None', '--VoilaExecutor.timeout=240']
 
 
 @pytest.fixture

tests/app/tree_test.py

@@ -9,7 +9,7 @@ def voila_args(notebook_directory, voila_args_extra):
 
 @pytest.fixture
 def voila_args_extra():
-    return ['--VoilaConfiguration.extension_language_mapping={".xcpp": "C++11"}']
+    return ['--VoilaConfiguration.extension_language_mapping={".xcpp": "C++11"}', '--VoilaExecutor.timeout=240']
 
 
 async def test_tree(http_server_client, base_url):

voila/handler.py

@@ -117,25 +117,8 @@ def redirect_to_file(self, path):
 
     async def _jinja_kernel_start(self):
         assert not self.kernel_started, "kernel was already started"
-        kernel_id = await self.kernel_manager.start_kernel(kernel_name=self.notebook.metadata.kernelspec.name, path=self.cwd)
-        km = self.kernel_manager.get_kernel(kernel_id)
-        # When Voila is launched as an app, its kernel manager's type is AsyncMappingKernelManager, and thus
-        # its kernel client's type is AsyncKernelClient.
-        # But this has to be explicitly configured when launched as a server extension, with e.g.:
-        # --ServerApp.kernel_manager_class=jupyter_server.services.kernels.kernelmanager.AsyncMappingKernelManager
-        # If it's not done, the kernel manager might not be async, which is not a big deal, but we want the kernel
-        # client to be async, so we explicitly configure it for this particular case:
-        km.client_class = 'jupyter_client.asynchronous.AsyncKernelClient'
-        self.executor = VoilaExecutor(self.notebook, km=km, config=self.traitlet_config)
-        self.executor.kc = km.client()
-        self.executor.kc.start_channels()
-        try:
-            await self.executor.kc.wait_for_ready(timeout=self.executor.startup_timeout)
-        except RuntimeError:
-            self.executor.kc.stop_channels()
-            self.executor.km.shutdown_kernel()
-            raise
-        self.executor.kc.allow_stdin = False
+        self.executor = VoilaExecutor(self.notebook, km=self.kernel_manager, config=self.traitlet_config)
+        kc, kernel_id = await self.executor.async_start_new_kernel_client(kernel_name=self.notebook.metadata.kernelspec.name, path=self.cwd)
         self.kernel_started = True
         return kernel_id
 
@@ -146,7 +129,7 @@ async def _jinja_notebook_execute(self, nb, kernel_id):
         # see the updated variable (it seems to be local to our block)
         nb.cells = result.cells
 
-    async def _jinja_cell_generator(self, nb, kernel_id):
+    async def _jinja_cell_generator(self, nb):
         """Generator that will execute a single notebook cell at a time"""
         nb, resources = ClearOutputPreprocessor().preprocess(nb, {'metadata': {'path': self.cwd}})