Fixing Java MySQL sample devfile to be able to be run on OSIO

[ScrewTSW]

What does this PR do?

This PR fixes the Java MySQL devfile memory quotas in order to be able to run the devfile on OSIO

What issues does this PR fix or reference?

Issue: https://github.com/redhat-developer/che-functional-tests/issues/556

[skabashnyuk]

CC @amisevsk

[amisevsk]

Looking at my quota usage with this devfile, I see 2.77Gi used out of 3Gi available; is there a reason we're not using the remaining ~230Mi quota?

[ScrewTSW]

Looking at my quota usage with this devfile, I see 2.77Gi used out of 3Gi available; is there a reason we're not using the remaining ~230Mi quota?

I can try to fiddle with it and submit a fix to the PR tomorrow.

[amisevsk]

Regardless I've tested and the lowered limit on java LS does not seem to interfere for the sample project. +1 to merge.

[amisevsk]

Looking at this more closely (output of top on the vscode-java container) I can see the language server being killed occasionally and restarted by the plugin. This is accompanied by logs like

[Info  - 2:59:18 PM] Connection to server got closed. Server will restart.
[Info  - 2:59:56 PM] Connection to server got closed. Server will restart.
[Error - 2:59:56 PM] Request textDocument/codeAction failed.
Error: Connection got disposed.
[...]

I also at one point ended up with two java language servers running simultaneously (though I don't know if that's an issue in master)

[ScrewTSW]

so upon investigation there are three constants consuming quota limits:

• JWT Proxy consumes 150MiB
• Machine exec pod consumes 150MiB
• Theia consumes 512MB = 488.281MiB

and the plugins defined in the devfile:

• mysql : 256MiB (+44MiB new value 300MiB)
• Java LSP : set to 1280MiB - Should be enough to avoid LSP OOM restart
• tools (maven) : 700MiB

That leaves me 1327.71875MiB to redistribute. After redistribution this leaves me exactly 3899392 bytes to spare or 3.71875MiB .

I've opened every single file, tried jump to definition, jump to implementation, code completion and code correction.

mysql peaked at 245MiB
Java LSP peaked at 950MiB and remained stable
Maven peaked at 350 MiB during build and then around 380 during application deployment