[bug] tsgo --build uses extreme amounts of memory

Stack trace

Unfortunately I don't have one to share as it crashed my remote dev machine (used 116GB of RSS before it did).

Steps to reproduce

This is probably unique to our scale here at Canva. I attempted to build one of the TS projects in our monorepo that transitively depends upon 5k+ other TS projects. It built for ~5 mins before crashing out due to excess memory usage.

./built/local/tsgo --build ../canva/<omitted>/tsconfig.json

Can you please try #1623 and see if that helps

Sheetal Nandi (@sheetalkamat)

Sheetal Nandi (@sheetalkamat) I just tried it out again with your change included -- unfortunately still seems to be broken. memory climbed back up to 100GB RSS before the OS killed the process. we could try to take a pprof memory profile beginning of next week if you'd find it useful?

$ strings ./built/local/tsgo | grep -i 15ae26ccc
mod     github.com/microsoft/typescript-go      v0.0.0-20250822042943-15ae26cccfb7
build   vcs.revision=15ae26cccfb7cd863aa009d0171715721d6785e1

Sheetal Nandi (@sheetalkamat)

Sheetal Nandi (@sheetalkamat)

following up Michael James (@mjames-c) -- with profiles attached for one of our largest TS projects:

typescript-cpuprof.gz

typescript-memprof.gz

happy to provide some more profiles of smaller projects if that'll be useful as well.

Johnny Cheng (@johnnycheng0210)

Johnny Cheng (@johnnycheng0210) can you see if you repro this if you run --singleThreaded

Can you try #1692 to see if it helps. You can also use --maxConcurrentProjects to change how many projects can be built simultaneously and see if that is of any help

Sheetal Nandi (@sheetalkamat)

Sheetal Nandi (@sheetalkamat) We faced the same problem (even with --noEmit) of tsgo taking more memory than tsc. Using --singleThreaded resolved the problem, while still allowing us to take advantage of the performance gains. Thanks for the tip!

Edit: One additional thing that can be tuned is GOGC (see docs) and GOMEMLIMIT (see docs). We set GOGC to 0.3 and GOMEMLIMIT to something less than our CI servers' limit

Can you please try out #1745 to see if it helps

Thanks

Sheetal Nandi (@sheetalkamat)

Sheetal Nandi (@sheetalkamat) have been seeing this too on a mix of individual projects or large subsets (8k projects) in our internal monorepo, how can I help test the PR? Build locally?

I might have missed where to find the branch deploy options 🙈🙏

You would need to build from #1745 to test it out

7.0.0-dev.20251208.1

I have the same issue in our repo, we have ~1000 ts projects, building everything in single process went up to 80GB commit size, based on error messages, didn't get much further than perhaps 5%, then crashed with oom.

Running --singleThreaded works fine, everything compiles, result is still much much faster than with tsc.

Sheetal Nandi (@sheetalkamat)

Sheetal Nandi (@sheetalkamat) Can you resurrect your change to limit the number of concurrent project builds? We have --checkers, but I think we were also wanting to add --builders to control that number.

Tomorrow, can you all try build mode with --builders 1? Given single project checking is already concurrent, we think it might be that build more concurrency may not actually matter too much anymore.

Is that expected to impact the LSP or should there be a separate issue for the LSP?

No, that is largely unrelated and not the focus of this thread. Build mode is not a part of the language server.

#2239 is closer, but I would very much suggest filing separate issues rather than commenting on existing ones if the cases aren't the same.

Jake Bailey (@jakebailey)

Jake Bailey (@jakebailey) I ran the test now with 7.0.0-dev.20251212.1

--clean called before both runs.

tsgo -b everything.json --singleThreaded - 3min 30sec to complete ~1000 tsconfig projects. ~30 sec to first error printed. Max commit size ~15GB

tsgo -b everything.json --builders 1 - 5 minutes without any output, i manually killed it. max commit size ~30GB (reached early, didn't grow much afterwards). For long periods the process seems to be idle for noticeable time, then work again, then again idle (cpu and mem doesn't move).

Is this codebase public? That definitely sounds like the opposite of how it should behave.

Unfortunately, very private. Perhaps if you are willing, we could try NDA path to get access to it. Overall it is just a lot of react tsx files and jest and playwright spec files, with declaration emit only. Few symlinks between packages, but mostly uses path aliases still.

btw, tsgo -b everything.json --builders 1 --checkers 1 have the same behavior as simply --builders 1 - still 30GB commit size and hangs.

Also the processes hang so that i can't even kill them via task manager - it shows access denied error.

taskkill /f /im tsgo.exe
ERROR: The process "tsgo.exe" with PID 14024 could not be terminated.
Reason: There is no running instance of the task.
ERROR: The process "tsgo.exe" with PID 36272 could not be terminated.
Reason: There is no running instance of the task.

Jake Bailey (@jakebailey)

Jake Bailey (@jakebailey) Sheetal Nandi (@sheetalkamat) - Managed to see high memory by typechecking a larger project (and hence it's dependents). Interestingly, the tsc version has different aggregate stats, and is suspiciously "fast" 🤔 So either I've cooked the test (though I tried to run clean a lot!) or something else is afoot!

When running on larger projects that went OOM, the pprof files were empty - so hopefully this is "large enough"? Let me know.
Details and profiles below, let me know if I've missed anything (or misconfigured the runs).

No rush on anything, just wanted to send while it was top of mind - happy holidays!

$ tsc --version
Version 5.9.2

$ tsgo --version
Version 7.0.0-dev.20251229.1

tsgo

tsgo --build ./foo/bar/baz/tsconfig.app.json --extendedDiagnostics --pprofDir $HOME/tmp/tsgo_profiling

ExtendedDiagnostics

Projects in scope:                       959
Projects built:                          959
Timestamps only updates:                   0
Aggregate Files:                      802216
Aggregate Lines:                   177931775
Aggregate Identifiers:             170526142
Aggregate Symbols:                 136494125
Aggregate Types:                     8362450
Aggregate Instantiations:           57375910
Aggregate Memory used:          10166117116K
Aggregate Memory allocs:        876822104759
Aggregate Config time:               38.296s
Aggregate BuildInfo read time:        0.017s
Aggregate Parse time:               804.888s
Aggregate Bind time:                  0.085s
Aggregate Check time:               106.868s
Aggregate Emit time:                546.251s
Aggregate Changes compute time:      69.540s
Aggregate Total time:               373.971s

--builders=1

tsgo --build ./foo/bar/baz/tsconfig.app.json--extendedDiagnostics --builders 1 --pprofDir $HOME/tmp/tsgo_profiling

ExtendedDiagnostics

Projects in scope:                       959
Projects built:                          959
Timestamps only updates:                   0
Aggregate Files:                      802216
Aggregate Lines:                   177931775
Aggregate Identifiers:             170526142
Aggregate Symbols:                 136494353
Aggregate Types:                     8362430
Aggregate Instantiations:           57375963
Aggregate Memory used:           7369865774K
Aggregate Memory allocs:        874861965624
Aggregate Config time:               44.783s
Aggregate BuildInfo read time:        0.008s
Aggregate Parse time:                27.321s
Aggregate Bind time:                  0.015s
Aggregate Check time:                38.933s
Aggregate Emit time:                138.541s
Aggregate Changes compute time:       6.523s
Aggregate Total time:              1120.233s

tsc

tsc --build ./foo/bar/baz/tsconfig.app.json --extendedDiagnostics

ExtendedDiagnostics

Projects in scope:                         959
Projects built:                            959
Aggregate Files:                        845214
Aggregate Lines of Library:           48370444
Aggregate Lines of Definitions:      131157035
Aggregate Lines of TypeScript:         2980402
Aggregate Lines of JavaScript:               0
Aggregate Lines of JSON:                 15745
Aggregate Lines of Other:                    0
Aggregate Identifiers:               180215539
Aggregate Symbols:                   129157294
Aggregate Types:                       4518690
Aggregate Instantiations:             21284442
Aggregate Memory used:                3505480K
Aggregate Assignability cache size:    2558219
Aggregate Identity cache size:           88349
Aggregate Subtype cache size:            60273
Aggregate Strict subtype cache size:     85158
Aggregate I/O Read time:                 8.60s
Aggregate Parse time:                    5.31s
Aggregate ResolveModule time:            8.11s
Aggregate ResolveTypeReference time:     0.30s
Aggregate ResolveLibrary time:           0.86s
Aggregate Program time:                 49.96s
Aggregate Bind time:                     2.63s
Aggregate Check time:                   51.27s
Aggregate transformTime time:           58.34s
Aggregate commentTime time:              0.57s
Aggregate I/O Write time:                4.45s
Aggregate printTime time:               73.41s
Aggregate Emit time:                    73.50s
Config file parsing time:                3.95s
Up-to-date check time:                   0.15s
Build time:                            200.79s

Profiles

tsgo

34030-cpuprofile.pb.gz
34030-memprofile.pb.gz

tsgo --builders=1

54771-cpuprofile.pb.gz
54771-memprofile.pb.gz

Sharing incase relevant- I also note that tsgolint has seen some similar performance struggles and there's some preliminary analysis pointing to resolution/strings in oxc-project/tsgolint#295 - though I'm not sure how much is tsgo, vs tsgolint's wrappers

Can you please try build from #2604 to see if it helps

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[bug] `tsgo --build` uses extreme amounts of memory #1622

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[bug] tsgo --build uses extreme amounts of memory #1622

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sheetalkamat commented on Aug 22, 2025

mjames-c commented on Aug 22, 2025

johnnycheng0210 commented on Aug 25, 2025

sheetalkamat commented on Aug 25, 2025

sheetalkamat commented on Sep 8, 2025

hsource commented on Sep 11, 2025

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spanishpear commented on Dec 30, 2025

tsgo

--builders=1

tsc

Profiles

tsgo

tsgo --builders=1

spanishpear commented on Dec 30, 2025

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jakebailey commented on Jan 7, 2026

sheetalkamat commented on Jan 29, 2026

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[bug] `tsgo --build` uses extreme amounts of memory #1622