Investigate slow response times for completion for LCLS.

[mrglavas]

While testing one of our recent drivers on my Windows 11 workstation, I'm noticing observably slow response times for completion requests in server.xml.

The user can see that something is loading, but I've observed it's taking up to 6 seconds just to display a list of feature names.

[Trace - 12:58:01] Received response 'textDocument/completion - (56)' in 5978ms.

[turkeylurkey]

On Mac. The first time I do the above it takes 154ms. The second time it takes less, 72ms.

[mrglavas]

It is consistently slow for me. Doesn't get any faster the 2nd time I try. I wonder if there's some network call in the background to build that list, for example from a schema that isn't being cached and that could be arbitrarily slow depending on your environment. It's worth noting that similar slow performance has been observed during SVT testing: #689.

[turkeylurkey]

Tested on Windows with lemminx 0.27.0, same issue.

[turkeylurkey]

On Windows. Editing pom.xml presumably the liberty extension is not used. Here the first completion takes 3.7s and the second takes 165ms. Generating elements inside the <project> element.

Generating the completion for this element took 35ms

[turkeylurkey]

On Windows. In bootstrap.properties generating this long list of options took 102ms

In server.env this shorter list took 24ms

[TrevCraw]

Just wanting to note the information reported by @Jonathan-Maciel in this issue during SVT:

Liberty Tools Driver: 24.0.3-SNAPSHOT
Windows 11 VM with 16GB RAM
IntelliJ IDEA 2023.3.4 (Community Edition)
OpenJDK 18.0.2

Hovering a feature does not display the documentation:

The response time is consistently over 2.5 seconds:

The feature completion also takes over 10 seconds:

[TrevCraw]

Performance degradation while editing server.xml has also been observed in Liberty Tools for Eclipse (starting in 23.0.9 or 23.0.12 - still investigating) and Liberty Tools for VS Code (starting in version 23.0.9).

Issue open for LT VS Code: OpenLiberty/liberty-tools-vscode#329