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.venv/Lib/site-packages/jupyter_client/ioloop/restarter.py

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+"""A basic in process kernel monitor with autorestarting.
+
+This watches a kernel's state using KernelManager.is_alive and auto
+restarts the kernel if it dies.
+"""
+# Copyright (c) Jupyter Development Team.
+# Distributed under the terms of the Modified BSD License.
+import asyncio
+import time
+import warnings
+
+from traitlets import Instance
+from zmq.eventloop import ioloop
+
+from jupyter_client.restarter import KernelRestarter
+from jupyter_client.utils import run_sync
+
+
+class IOLoopKernelRestarter(KernelRestarter):
+    """Monitor and autorestart a kernel."""
+
+    loop = Instance("tornado.ioloop.IOLoop")
+
+    def _loop_default(self):
+        warnings.warn(
+            "IOLoopKernelRestarter.loop is deprecated in jupyter-client 5.2",
+            DeprecationWarning,
+            stacklevel=4,
+        )
+        return ioloop.IOLoop.current()
+
+    _pcallback = None
+
+    def start(self):
+        """Start the polling of the kernel."""
+        if self._pcallback is None:
+            if asyncio.iscoroutinefunction(self.poll):
+                cb = run_sync(self.poll)
+            else:
+                cb = self.poll
+            self._pcallback = ioloop.PeriodicCallback(
+                cb,
+                1000 * self.time_to_dead,
+            )
+            self._pcallback.start()
+
+    def stop(self):
+        """Stop the kernel polling."""
+        if self._pcallback is not None:
+            self._pcallback.stop()
+            self._pcallback = None
+
+
+class AsyncIOLoopKernelRestarter(IOLoopKernelRestarter):
+    async def poll(self):
+        if self.debug:
+            self.log.debug("Polling kernel...")
+        is_alive = await self.kernel_manager.is_alive()
+        now = time.time()
+        if not is_alive:
+            self._last_dead = now
+            if self._restarting:
+                self._restart_count += 1
+            else:
+                self._restart_count = 1
+
+            if self._restart_count > self.restart_limit:
+                self.log.warning("AsyncIOLoopKernelRestarter: restart failed")
+                self._fire_callbacks("dead")
+                self._restarting = False
+                self._restart_count = 0
+                self.stop()
+            else:
+                newports = self.random_ports_until_alive and self._initial_startup
+                self.log.info(
+                    "AsyncIOLoopKernelRestarter: restarting kernel (%i/%i), %s random ports",
+                    self._restart_count,
+                    self.restart_limit,
+                    "new" if newports else "keep",
+                )
+                self._fire_callbacks("restart")
+                await self.kernel_manager.restart_kernel(now=True, newports=newports)
+                self._restarting = True
+        else:
+            # Since `is_alive` only tests that the kernel process is alive, it does not
+            # indicate that the kernel has successfully completed startup. To solve this
+            # correctly, we would need to wait for a kernel info reply, but it is not
+            # necessarily appropriate to start a kernel client + channels in the
+            # restarter. Therefore, we use "has been alive continuously for X time" as a
+            # heuristic for a stable start up.
+            # See https://github.com/jupyter/jupyter_client/pull/717 for details.
+            stable_start_time = self.stable_start_time
+            if self.kernel_manager.provisioner:
+                stable_start_time = self.kernel_manager.provisioner.get_stable_start_time(
+                    recommended=stable_start_time
+                )
+            if self._initial_startup and now - self._last_dead >= stable_start_time:
+                self._initial_startup = False
+            if self._restarting and now - self._last_dead >= stable_start_time:
+                self.log.debug("AsyncIOLoopKernelRestarter: restart apparently succeeded")
+                self._restarting = False