Avoid acquiring the workspace lock on the UI thread if unneeded #79025
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If the project system tells us about a file that's open and we are told about it on a background thread, we connect the file to the workspace on that background thread but then schedule work to the UI thread to ensure we correctly connect it to the right context (linked files, shared projects, multitargeting, etc.) That code on the UI thread then acquires the workspace lock, and we're seeing cases in the wild where that lock acquisition is taking longer than we'd like. Although there are deeper fixes we can do there, there's one trivial fix we can make: don't schedule the work to the UI thread unless the file is in at least two projects. Otherwise, we don't actually need to figure out the context in the first place and it's just wasting time. An entirely unscientific analysis of a handful of traces from users hitting this, there weren't any cases where the file was actually in more than one project, so this should have a nice improvement overall. Closes https://devdiv.visualstudio.com/DevDiv/_workitems/edit/2471561
dibarbet
approved these changes
Jun 17, 2025
JoeRobich
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Jun 18, 2025
CyrusNajmabadi
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Jun 18, 2025
…ed (dotnet#79025)" This reverts commit f479243, reversing changes made to 438638e.
CyrusNajmabadi
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If the project system tells us about a file that's open and we are told about it on a background thread, we connect the file to the workspace on that background thread but then schedule work to the UI thread to ensure we correctly connect it to the right context (linked files, shared projects, multitargeting, etc.) That code on the UI thread then acquires the workspace lock, and we're seeing cases in the wild where that lock acquisition is taking longer than we'd like. Although there are deeper fixes we can do there, there's one trivial fix we can make: don't schedule the work to the UI thread unless the file is in at least two projects. Otherwise, we don't actually need to figure out the context in the first place and it's just wasting time.
An entirely unscientific analysis of a handful of traces from users hitting this, there weren't any cases where the file was actually in more than one project, so this should have a nice improvement overall.
Closes https://devdiv.visualstudio.com/DevDiv/_workitems/edit/2471561