delay project system init to avoid solution update race

[corngood]

I've been getting this error intermittently:

omnisharp-roslyn/src/OmniSharp.MSBuild/ProjectManager.cs

Line 375 in 8f3b6ea

_logger.LogError($"Failed to add project to workspace: '{projectFileInfo.FilePath}'");

I tracked it down to a race between TryApplyChanges calls.

Adding the project happens on a worker thread, and is queued on the main thread inside:

omnisharp-roslyn/src/OmniSharp.Host/WorkspaceInitializer.cs

Line 43 in 8f3b6ea

projectSystem.Initalize(projectConfiguration);

I believe AddProject can be called on a worker thread any time after this.

The other call is on the main thread via:

omnisharp-roslyn/src/OmniSharp.Host/WorkspaceInitializer.cs

Line 59 in 8f3b6ea

ProvideWorkspaceOptions(compositionHost, workspace, options, logger, omnisharpEnvironment);

omnisharp-roslyn/src/OmniSharp.Host/WorkspaceInitializer.cs

Line 91 in 8f3b6ea

if (!workspace.TryApplyChanges(workspace.CurrentSolution.WithOptions(workspaceOptionsProvider.Process(workspace.Options, options.CurrentValue, omnisharpEnvironment))))

This change rearranges workspace init to avoid this particular race. It doesn't seem like anything attempts to retry solution changes, so if there are other races it may be a more serious problem.

[dnfadmin]

All CLA requirements met.

[filipw]

LGTM

[filipw]

@JoeRobich @david-driscoll @mholo65 do you have any comments on this?

[filipw]

thanks!