Skip to content

Commit

Permalink
Merge pull request #8189 from blink1073/slow-kernel-start-3
Browse files Browse the repository at this point in the history 
[BackPort] Better handling of slow kernel startup
  • Loading branch information
@afshin
afshin committed Apr 8, 2020
2 parents 16a652c + c9206d9 commit b52a310
Show file tree
Hide file tree
Showing 6 changed files with 232 additions and 95 deletions.
3 changes: 3 additions & 0 deletions examples/cell/src/index.ts
View file
Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,9 @@ function main(): void {

// Handle the mimeType for the current kernel.
session.kernelChanged.connect(() => {
if (!session.kernel) {
return;
}
void session.kernel.ready.then(() => {
const lang = session.kernel.info.language_info;
const mimeType = mimeService.getMimeTypeByLanguage(lang);
Expand Down
238 changes: 167 additions & 71 deletions packages/apputils/src/clientsession.tsx
View file
Original file line number Diff line number Diff line change
Expand Up @@ -316,10 +316,25 @@ export class ClientSession implements IClientSession {
* The current status of the session.
*/
get status(): Kernel.Status {
if (!this.isReady) {
if (this._session) {
return this._session.status;
}
if (this._pendingKernelName === Private.NO_KERNEL) {
return 'idle';
}
if (
!this.isReady &&
this.kernelPreference.canStart !== false &&
this.kernelPreference.shouldStart !== false
) {
return 'starting';
}

if (this._pendingKernelName) {
return 'starting';
}
return this._session ? this._session.status : 'dead';

return 'unknown';
}

/**
Expand All @@ -340,16 +355,36 @@ export class ClientSession implements IClientSession {
* The display name of the current kernel.
*/
get kernelDisplayName(): string {
let kernel = this.kernel;
if (!kernel) {
return 'No Kernel!';
let kernel = this._session ? this._session.kernel : null;
if (this._pendingKernelName === Private.NO_KERNEL) {
return Private.NO_KERNEL;
}
if (
!kernel &&
!this.isReady &&
this.kernelPreference.canStart !== false &&
this.kernelPreference.shouldStart !== false
) {
let name =
this._pendingKernelName ||
ClientSession.getDefaultKernel({
specs: this.manager.specs,
sessions: this.manager.running(),
preference: this.kernelPreference
}) ||
'';
if (name) {
return this._displayNameForKernelName(name);
}
return Private.NO_KERNEL;
}
let specs = this.manager.specs;
if (!specs) {
return 'Unknown!';
if (this._pendingKernelName) {
return this._displayNameForKernelName(this._pendingKernelName);
}
let spec = specs.kernelspecs[kernel.name];
return spec ? spec.display_name : kernel.name;
if (!kernel) {
return Private.NO_KERNEL;
}
return this._displayNameForKernelName(kernel.name);
}

/**
Expand All @@ -369,7 +404,7 @@ export class ClientSession implements IClientSession {
this._isDisposed = true;
if (this._session) {
if (this.kernelPreference.shutdownOnClose) {
this._session.shutdown().catch(reason => {
this.manager.shutdown(this._session.id).catch(reason => {
console.error(`Kernel not shut down ${reason}`);
});
}
Expand All @@ -389,22 +424,24 @@ export class ClientSession implements IClientSession {
/**
* Change the current kernel associated with the document.
*/
changeKernel(
async changeKernel(
options: Partial<Kernel.IModel>
): Promise<Kernel.IKernelConnection> {
return this.initialize().then(() => {
if (this.isDisposed) {
return Promise.reject('Disposed');
}
return this._changeKernel(options);
});
if (this.isDisposed) {
return Promise.reject('Disposed');
}
// Wait for the initialization method to try
// and start its kernel first to ensure consistent
// ordering.
await this._initStarted.promise;
return this._changeKernel(options);
}

/**
* Select a kernel for the session.
*/
selectKernel(): Promise<void> {
return this.initialize().then(() => {
return this._initStarted.promise.then(() => {
if (this.isDisposed) {
return Promise.reject('Disposed');
}
Expand All @@ -417,13 +454,14 @@ export class ClientSession implements IClientSession {
*
* @returns A promise that resolves when the session is shut down.
*/
shutdown(): Promise<void> {
const session = this._session;
if (this.isDisposed || !session) {
return Promise.resolve();
async shutdown(): Promise<void> {
if (this.isDisposed || !this._initializing) {
return;
}
this._session = null;
return session.shutdown();
await this._initStarted.promise;
this._pendingSessionRequest = '';
this._pendingKernelName = Private.NO_KERNEL;
return this._shutdownSession();
}

/**
Expand Down Expand Up @@ -524,23 +562,32 @@ export class ClientSession implements IClientSession {
return this._ready.promise;
}
this._initializing = true;
await this._intialize();
this._isReady = true;
this._ready.resolve(undefined);
if (!this._pendingSessionRequest) {
this._initStarted.resolve(void 0);
}
}

async _intialize(): Promise<void> {
let manager = this.manager;
await manager.ready;
await manager.refreshRunning();
let model = find(manager.running(), item => {
return item.path === this._path;
});
if (model) {
try {
let session = manager.connectTo(model);
this._handleNewSession(session);
return;
} catch (err) {
void this._handleSessionError(err);
return Promise.reject(err);
}
}
await this._startIfNecessary();
this._isReady = true;
this._ready.resolve(undefined);
}

/**
Expand Down Expand Up @@ -578,20 +625,55 @@ export class ClientSession implements IClientSession {
/**
* Change the kernel.
*/
private _changeKernel(
options: Partial<Kernel.IModel>
private async _changeKernel(
model: Partial<Kernel.IModel>
): Promise<Kernel.IKernelConnection> {
if (this.isDisposed) {
return Promise.reject('Disposed');
this._pendingKernelName = model.name;

if (this._session) {
await this._shutdownSession();
} else {
this._kernelChanged.emit({
oldValue: null,
newValue: null
});
}
let session = this._session;
if (session && session.status !== 'dead') {
return session.changeKernel(options).catch(err => {
void this._handleSessionError(err);
return Promise.reject(err);

// Guarantee that the initialized kernel
// will be started first.
if (!this._pendingSessionRequest) {
this._initStarted.resolve(void 0);
}
const requestId = (this._pendingSessionRequest = UUID.uuid4());
try {
// Use a UUID for the path to overcome a race condition on the server
// where it will re-use a session for a given path but only after
// the kernel finishes starting.
// We later switch to the real path below.
this._statusChanged.emit('starting');
const session = await this.manager.startNew({
path: requestId,
type: this._type,
name: this._name,
kernelName: model.name,
kernelId: model.id
});
} else {
return this._startSession(options);
// Handle a preempt.
if (this._pendingSessionRequest !== session.path) {
await session.shutdown();
session.dispose();
return null;
}
// Change to the real path.
await session.setPath(this._path);

if (this._session) {
await this._shutdownSession();
}
return this._handleNewSession(session);
} catch (err) {
void this._handleSessionError(err);
throw err;
}
}

Expand Down Expand Up @@ -621,12 +703,9 @@ export class ClientSession implements IClientSession {
return;
}
let model = result.value;
if (model === null && this._session) {
return this.shutdown().then(() => {
this._kernelChanged.emit({ oldValue: null, newValue: null });
});
}
if (model) {
if (model === null) {
return this.shutdown();
} else {
return this._changeKernel(model).then(() => undefined);
}
})
Expand All @@ -635,32 +714,6 @@ export class ClientSession implements IClientSession {
});
}

/**
* Start a session and set up its signals.
*/
private _startSession(
model: Partial<Kernel.IModel>
): Promise<Kernel.IKernelConnection> {
if (this.isDisposed) {
return Promise.reject('Session is disposed.');
}
return this.manager
.startNew({
path: this._path,
type: this._type,
name: this._name,
kernelName: model ? model.name : undefined,
kernelId: model ? model.id : undefined
})
.then(session => {
return this._handleNewSession(session);
})
.catch(err => {
void this._handleSessionError(err);
return Promise.reject(err);
});
}

/**
* Handle a new session object.
*/
Expand Down Expand Up @@ -694,10 +747,12 @@ export class ClientSession implements IClientSession {
session.iopubMessage.connect(this._onIopubMessage, this);
session.unhandledMessage.connect(this._onUnhandledMessage, this);
this._prevKernelName = session.kernel.name;
this._pendingKernelName = '';

// The session kernel was disposed above when the session was disposed, so
// the oldValue should be null.
this._kernelChanged.emit({ oldValue: null, newValue: session.kernel });
this._statusChanged.emit('unknown');
return session.kernel;
}

Expand Down Expand Up @@ -737,6 +792,31 @@ export class ClientSession implements IClientSession {
this._dialog = null;
}

/**
* Shut down the current session.
*/
async _shutdownSession(): Promise<void> {
const session = this._session;
this._session = null;
this._statusChanged.emit('idle');

if (!session) {
this._kernelChanged.emit({
oldValue: null,
newValue: null
});
return;
}
const kernel = session.kernel || null;
this._kernelChanged.emit({
oldValue: kernel,
newValue: null
});

await session.shutdown();
session.dispose();
}

/**
* Handle a session termination.
*/
Expand Down Expand Up @@ -826,6 +906,14 @@ export class ClientSession implements IClientSession {
this._unhandledMessage.emit(message);
}

/**
* Get the display name for a kernel name.
*/
private _displayNameForKernelName(name: string) {
const spec = this.manager.specs.kernelspecs[name];
return spec ? spec.display_name : name;
}

private _path = '';
private _name = '';
private _type = '';
Expand All @@ -835,6 +923,7 @@ export class ClientSession implements IClientSession {
private _session: Session.ISession | null = null;
private _ready = new PromiseDelegate<void>();
private _initializing = false;
private _initStarted = new PromiseDelegate<void>();
private _isReady = false;
private _terminated = new Signal<this, void>(this);
private _kernelChanged = new Signal<this, Session.IKernelChangedArgs>(this);
Expand All @@ -845,6 +934,8 @@ export class ClientSession implements IClientSession {
private _dialog: Dialog<any> | null = null;
private _setBusy: () => IDisposable | undefined;
private _busyDisposable: IDisposable | null = null;
private _pendingKernelName = '';
private _pendingSessionRequest = '';
}

/**
Expand Down Expand Up @@ -971,6 +1062,11 @@ export namespace ClientSession {
* The namespace for module private data.
*/
namespace Private {
/**
* The text to show for no kernel.
*/
export const NO_KERNEL = 'No Kernel';

/**
* A widget that provides a kernel selection.
*/
Expand Down Expand Up @@ -1249,7 +1345,7 @@ namespace Private {
let group = document.createElement('optgroup');
group.label = 'Use No Kernel';
let option = document.createElement('option');
option.text = 'No Kernel';
option.text = Private.NO_KERNEL;
option.value = 'null';
group.appendChild(option);
return group;
Expand Down

0 comments on commit b52a310

Please sign in to comment.