Explorer can freeze for large folders and many glob patterns

[PowerSnail]

• VSCode Version: 1.3.1
• OS Version: Windows 10 Pro

Steps to Reproduce:

1. Open a folder from visual studio code
2. In the sidebar, select a subfolder with a huge number of files (mine has over 70000 json files)

Then the window will just freeze. No response to click or keyboard whatsoever, until after a while the system reports that "The Window is no longer responding".

Thank you!

[bpasero]

Tree performance... I have seen this as well when opening the typescript workspace where they have one test folder with many thousand files. Maybe worth looking into a performance trace there to see what can be done.

[bpasero]

This cannot be important because we shipped with this for years.

[bpasero]

When I open the tests/baseline folder of the TypeScript workspace (it includes 18000 files) it takes 30 seconds to show the contents (not seeing any progress during which, filed #10459).

@joaomoreno most time seems to be spend in the treeModel#Item() function, can you take a look? The profile is here: explorer.cpuprofile.zip

One thing to note is that the explorer is not using templates yet but I would not expect that to be a problem for 18.000 elements where most of them show hidden. Only a problem when quickly scrolling through the results.

[joaomoreno]

Just comment out this section and you'll get rid of the UI performance bottleneck. And obviously so: every filter call is going through all the sibling files, for every file, making this O(n²).

It immediately becomes more responsive, although it still takes ~5 seconds on my machine. Most of that time is spent on the file service and the file viewer classes:

[bpasero]

I pushed a fix that avoids the O(n^2) issue for most cases but if the user has configured a filter pattern where I need to know the siblings ("**/*.js": { "when": "$(basename).ts" }) we still run into the performance issue, so I am leaving this open.

[bpasero]

Pushed another fix to ignore glob patterns that need to check on siblings when the number of files in a folder exceed a threshold.

Expanding the typescript/test/baseline folder with 16.000 files still takes 3-4 seconds but is much better compared to the 30-60 seconds we used to have. Closing.