improve plugins loading

[akosyakov]

What it does

• partially addresses plugin system does not scale over JSON-RPC #6228 extracted from don't block web socket with many plugins #6252:
  • use permessage-deflate to compress any ws message greater than 256kb
  • only fetch not yet loaded plugins to the frontend
  • initialize debugger contributions from metadata, instead of sending it first to the plugin host and then back to the frontend
• closes don't send plugin metadata over JSON-RPC #6233 - superseded
• also addresses don't block web socket with many plugins #6252 (comment)

How to test

• remove native extension from the browse example and rebuild:
  • textmate grammar
  • debug-nodejs
  • java
  • java-debug
• install 57 VS Code extensions in plugins folder:
  https://drive.google.com/file/d/1tuOsorMVOKi_twL9oAuZxgrD7-VUwNsj/view?usp=sharing
  • could not come up with a command to pull it from the gdrive in the terminal, if someone knows how to, please share
• use system proxy to emulate slow connection, e.g. Charles proxy
  • you cannot do it in Chrome, since it cannot throttle web sockets
• measure how long does it takes to activate all plugins before and after
• observe whether you get yellow status bar and ws frames hangs for 20-30 seconds after and before
• play with unstable connections to confirm that plugins get reloaded/unloaded on the reconnection

Review checklist

• as an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• as a reviewer, I agree to behave in accordance with the review guidelines

[benoitf]

hello, why do we have yet another PR than #6252 ?
is it to bypass requested changes/discussion on the other PR ?

[akosyakov]

@benoitf no, I follow your suggestions, from #6252 (comment):

remove 2 commits from PR and merge it (but it won't solve the blocking)

Or you are going to review changes to mentioned 2 commits?

[benoitf]

@akosyakov I will review the two commits

[benoitf]

for me this PR is fine but it is not solving all the issues, so I would better use #6252

[akosyakov]

I don't see yellow status bar with this PR as well, but numbers on 3G are not so good as with #6252

• fetching plugins: 3872.8999998420477 ms vs 2785.3900000918657 ms
• starting plugins: 7810.244999825954 ms vs 1804.2249998543411 ms

[svenefftinge]

I'd prefer to go with #6252, too.

[akosyakov]

Closing since #6252 is merged.