If we fail to start a raw kernel daemon, fall back on process execution (microsoft#12736)

Co-authored-by: Ian Huff <ianhuff@ravikun-dev2.redmond.corp.microsoft.com>

Author: IanMatthewHuff

news/2 Fixes/12355.md

@@ -0,0 +1 @@
+If we fail to start a raw kernel daemon then fall back to using process execution.

src/client/datascience/kernel-launcher/kernelLauncherDaemon.ts

@@ -27,8 +27,15 @@ export class PythonKernelLauncherDaemon implements IDisposable {
  resource: Resource,
  kernelSpec: IJupyterKernelSpec,
  interpreter?: PythonInterpreter
- ): Promise<{ observableOutput: ObservableExecutionResult<string>; daemon: IPythonKernelDaemon }> {
+ ): Promise<{ observableOutput: ObservableExecutionResult<string>; daemon: IPythonKernelDaemon } | undefined> {
  const daemon = await this.daemonPool.get(resource, kernelSpec, interpreter);
+
+ // The daemon pool can return back a non-IPythonKernelDaemon if daemon service is not supported or for Python 2.
+ // Use a check for the daemon.start function here before we call it.
+ if (!daemon.start) {
+ return undefined;
+ }
+
  const args = kernelSpec.argv.slice();
  const modulePrefixIndex = args.findIndex((item) => item === '-m');
  if (modulePrefixIndex === -1) {

src/client/datascience/kernel-launcher/kernelProcess.ts

@@ -215,17 +215,23 @@ export class KernelProcess implements IKernelProcess {
  }
 
  private async launchAsObservable() {
- let exeObs: ObservableExecutionResult<string>;
+ let exeObs: ObservableExecutionResult<string> | undefined;
  if (this.isPythonKernel) {
  this.pythonKernelLauncher = new PythonKernelLauncherDaemon(this.daemonPool);
- const { observableOutput, daemon } = await this.pythonKernelLauncher.launch(
+ const kernelDaemonLaunch = await this.pythonKernelLauncher.launch(
  this.resource,
  this._kernelSpec,
  this.interpreter
  );
- this.kernelDaemon = daemon;
- exeObs = observableOutput;
- } else {
+
+ if (kernelDaemonLaunch) {
+ this.kernelDaemon = kernelDaemonLaunch.daemon;
+ exeObs = kernelDaemonLaunch.observableOutput;
+ }
+ }
+
+ // If we are not python or if we failed with our daemon launch just use the ProcessExecutionFactory
+ if (!exeObs) {
  // First part of argument is always the executable.
  const executable = this._kernelSpec.argv[0];
  const executionService = await this.processExecutionFactory.create(this.resource);
@@ -234,7 +240,7 @@ export class KernelProcess implements IKernelProcess {
  });
  }
 
- if (exeObs.proc) {
+ if (exeObs && exeObs.proc) {
  exeObs.proc.on('exit', (exitCode) => {
  traceInfo('KernelProcess Exit', `Exit - ${exitCode}`);
  if (this.disposed) {

src/test/datascience/kernel-launcher/kernelLauncherDaemon.unit.test.ts

@@ -52,9 +52,19 @@ suite('Data Science - Kernel Launcher Daemon', () => {
  await assert.isRejected(promise, /^Unsupported KernelSpec file. args must be/g);
  });
  test('Creates and returns a daemon', async () => {
- const { observableOutput, daemon } = await launcher.launch(undefined, kernelSpec, interpreter);
+ const daemonCreationOutput = await launcher.launch(undefined, kernelSpec, interpreter);
 
- assert.equal(observableOutput, instance(observableOutputForDaemon));
- assert.equal(daemon, instance(kernelDaemon));
+ assert.isDefined(daemonCreationOutput);
+
+ if (daemonCreationOutput) {
+ assert.equal(daemonCreationOutput.observableOutput, instance(observableOutputForDaemon));
+ assert.equal(daemonCreationOutput.daemon, instance(kernelDaemon));
+ }
+ });
+ test('If our daemon pool return does not support start, return undefined', async () => {
+ when(daemonPool.get(anything(), anything(), anything())).thenResolve({} as any);
+ const daemonCreationOutput = await launcher.launch(undefined, kernelSpec, interpreter);
+
+ assert.isUndefined(daemonCreationOutput);
  });
 });