Loading Roslyn takes a long time and is almost silent

[agocke]

My daily workflow is to navigate to a project like Roslyn in the terminal, run code ., and begin to edit.

Omnisharp's project loading strategy is slow and difficult to track. First, the only way I seem to be able to figure out when Omnisharp is loaded is watching for Code Lens. Compare the before and after pictures here:

Before:

After:

The first picture is before the project is loaded, while the second is after. "Run Test | Debug Test" is the only obvious difference.

The other problem is that it takes a long time to load, even if the solution context is exactly the same. If I close VS Code and then re-open it in the exact same directory without changing any files, the time between when VS Code is open and the solution is loaded is 87 seconds. This is on a reasonably powerful i7-7700 desktop machine with 65 GB of memory. In contrast, it took 27 seconds in Visual Studio.

On the other hand, VS blocked the UI thread during this time. This is worse in some sense, but it's also feedback that indicates when semantic analysis is available.

[filipw]

thanks for the issue, unfortunately there isn't any reliable load progress support at the moment (from that perspective this is the same as mentioned here #1521)

VS Code extension used to indicate readiness by turning the OmniSharp icon to green at the bottom, but that color was changed to always white despite my protests and now even that indicator is lost.

We have some prototypes of improving load times by parallelizing certain things.

[lspdude]

So LSPs don't save ASTs to ('cache') files? if there are 1000 files in a project, and user opens just one, all files are re-parsed?

Hmm .. if such popular tools ( C# VS code/VS) re-parse same files every time, maybe such 'caching' isn't practical.