Pass max_old_space_size to TSServer

[danielscottjames]

Per discussion here: microsoft/TypeScript#18055

Some things I noticed while looking into this:

• I believe either --max_old_space_size or --max-old-space-size works, v8 args can be dashes or underscores. Underscores work for sure.
• TSServer appears to have special logic if global.gc is available, so maybe consider adding --expose-gc as well.
• I believe the maximum settings for 64-bit builds of Node is 4096
• There's this: max_old_space_size doesn't work when running electron as node electron/electron#9693. Essentially when running VS Code with the ./script/code.sh script, setting these flags in execArgv options in typescriptserviceclient.ts had no effect. I think it'll work if Electron is packaged and ran normally, but I'm not positive.

[mjbvz]

I gave this a shot but was unable to get it working even when using a production build of VS Code. Looks like this is blocked by: electron/electron#10413 electron/electron#9693

[MLoughry]

@mjbvz I'm running into the same issue. Our project has to tsc with 4GB of memory, and investigations with @amcasey seem to indicate the issue is a lack of memory for tsserver.

It looks like both Electron issues are resolved, so is this issue now unblocked? It would be great if tsserver memory were configurable in workspace settings.

[mjbvz]

@MLoughry Can you try making the change and submit a PR if it works? Here's the code where we spawn the tsserver process:

vscode/extensions/typescript-language-features/src/tsServer/spawner.ts

Line 88 in f452455

private getForkOptions(kind: ServerKind) {

[MLoughry]

I'll try to set up an enlistment today/tomorrow and try adding a hard-coded value to see if it works. If it does, do you have a quick pointer on where the guide/code to add a new setting would be?

[amcasey]

@mjbvz We did an A/B test when VS made this change and OOMs did go down (as you might hope). When I debugged locally with @MLoughry, we also tried with VS (which passes max_old_space_size) and I don't believe we saw a server crash (though I didn't specifically look for one).

[mjbvz]

To verify:

1. Set "typescript.tsserver.maxTsServerMemory": 128
2. Now open VS Code
3. This should cause the TSServer to get into a bad state because we cannot load the VS Code project in that amount of memory
4. Now set it to "typescript.tsserver.maxTsServerMemory": 4000
5. The project should now load (you may need to restart VS Code)

[connor4312]

Works as specified and I can see that tsserver is started with --max-old-space-size=4000/128 through htop