Improve startup performance in VS Code #4634
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| @@ -153,6 +154,9 @@ private void OnUnregisterCapability(object sender, UnregisterCapabilityEventArgs | |||
| #region Workspace | |||
| [JsonRpcMethod("workspace/didChangeConfiguration")] | |||
| public async Task DidChangeConfiguration(JToken token, CancellationToken cancellationToken) { | |||
| // Change configuration comes right after the initialization | |||
| WaitForServerInitComplete(cancellationToken); | |||
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Why await server.CompleteInitialization isn't enough?
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It yields, we get next request. So we end up receiving requests without having initialization complete. One option to add await CompleteInitialization to sync context and call it before any request.
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But DidChangeConfiguration is called through sync context already. We have it in JsonRPC, right?
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It called sequentially but I do see the yield. Perhaps our sync context is incorrect.
| @@ -153,6 +157,9 @@ private sealed class ReloadModulesQueueItem : IAnalyzable { | |||
| } | |||
| }; | |||
| } | |||
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| internal Task CompleteInitialization { get; private set; } = Task.CompletedTask; | |||
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This isn't safe. Awaiter may reach CompleteInitialization before it is replaced. I'd rather go with TaskCompetionSource:
internal async Task<InitializeResult> Initialize(InitializeParams @params, CancellationToken cancellationToken) {
ThrowIfDisposed();
if (!@params.initializationOptions.asyncStartup) {
_completeInitializationTcs.TrySetCompleted(null);
}
using (_completeInitializationTcs.RegisterForCancellation(cancellationToken)) {
await DoInitializeAsync(@params, cancellationToken);
_completeInitializationTcs.TrySetCompleted(null);
}internal Task CompleteInitialization => _completeInitializationTcs.TaskThere was a problem hiding this comment.
Although point here is NOT to await on DoInitializeAsync and just let it run. Awaiting blocks VSC startup.
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Actually, nothing ever called until initialized returns. So I don't think the task can be replaced easily.
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So do I get it right that you want to wait for initialization to complete on the first request after initialization, rather than during initialization request itself?
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Yep. Those are 'open file' and 'change config' - they come after the init. Actually we need to debug why sync context does not wait for completions - or, rather, the StreamJsonRpc.
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I might need to use alternative implementation (from R/vsc) instead of sync context which actually makes sure requests do complete sequentially. See https://github.com/MikhailArkhipov/PTVS/blob/sync/Python/Product/VSCode/AnalysisVsc/LanguageServerProxy.cs
microsoft/vscode-python#1865
Basically restore async startup options we once had. This shortens wait time in VSC by ~30-40% (from 2s to 1.2s on the LS process startup. VSC it blocks between 'initialize' and 'initialized'.