Use paged link stores for all symbol links by jakebailey · Pull Request #64872 · microsoft/TypeScript

Jake Bailey (jakebailey) · 2026-10-19T17:46:30Z

Symbol links were stored in Go maps keyed by symbol pointer, so every link lookup paid for a hash and probe. Map lookups for symbol links were among the hottest leaf costs when checking large projects.

The paged store that already backs value symbol links indexes by the dense symbol ID instead, which is a couple of loads. Using it for the remaining symbol link kinds removes those map lookups, at the cost of under 1% more heap for the page tables.

--checkers 4, n=8, default GC settings:

                  │  before    │              after               │
                  │   sec/op   │   sec/op    vs base              │
Tsc/bluesky         2.826 ± 2%   2.799 ± 2%  -0.97% (p=0.015 n=8)
Tsc/sentry          11.13 ± 3%   10.86 ± 2%       ~ (p=0.083 n=8)
Tsc/t3code-server   13.97 ± 2%   13.89 ± 6%       ~ (p=0.645 n=8)
geomean             7.603        7.502       -1.32%

                  │   before     │               after                │
                  │    rss-B     │    rss-B      vs base              │
Tsc/bluesky         1.201Gi ± 2%   1.203Gi ± 2%       ~ (p=0.878 n=8)
Tsc/sentry          3.647Gi ± 9%   3.535Gi ± 6%       ~ (p=0.328 n=8)
Tsc/t3code-server   2.883Gi ± 4%   2.877Gi ± 3%       ~ (p=0.574 n=8)
geomean             2.328Gi        2.304Gi       -1.05%

                  │   before     │               after                │
                  │    heap-B    │    heap-B     vs base              │
Tsc/bluesky         934.8Mi ± 0%   934.8Mi ± 0%       ~ (p=0.798 n=8)
Tsc/sentry          2.583Gi ± 0%   2.603Gi ± 0%  +0.78% (p=0.000 n=8)
Tsc/t3code-server   2.295Gi ± 0%   2.312Gi ± 0%  +0.71% (p=0.000 n=8)
geomean             1.756Gi        1.765Gi       +0.50%

This is pretty small; want to check the real perf suite.

Symbol links were stored in Go maps keyed by symbol pointer, so every link lookup paid for a hash and probe. Map lookups for symbol links were among the hottest leaf costs when checking large projects. The paged store that already backs value symbol links indexes by the dense symbol ID instead, which is a couple of loads. Using it for the remaining symbol link kinds removes those map lookups, at the cost of under 1% more heap for the page tables. --checkers 4, n=8, default GC settings: │ before │ after │ │ sec/op │ sec/op vs base │ Tsc/bluesky 2.826 ± 2% 2.799 ± 2% -0.97% (p=0.015 n=8) Tsc/sentry 11.13 ± 3% 10.86 ± 2% ~ (p=0.083 n=8) Tsc/t3code-server 13.97 ± 2% 13.89 ± 6% ~ (p=0.645 n=8) geomean 7.603 7.502 -1.32% │ before │ after │ │ rss-B │ rss-B vs base │ Tsc/bluesky 1.201Gi ± 2% 1.203Gi ± 2% ~ (p=0.878 n=8) Tsc/sentry 3.647Gi ± 9% 3.535Gi ± 6% ~ (p=0.328 n=8) Tsc/t3code-server 2.883Gi ± 4% 2.877Gi ± 3% ~ (p=0.574 n=8) geomean 2.328Gi 2.304Gi -1.05% │ before │ after │ │ heap-B │ heap-B vs base │ Tsc/bluesky 934.8Mi ± 0% 934.8Mi ± 0% ~ (p=0.798 n=8) Tsc/sentry 2.583Gi ± 0% 2.603Gi ± 0% +0.78% (p=0.000 n=8) Tsc/t3code-server 2.295Gi ± 0% 2.312Gi ± 0% +0.71% (p=0.000 n=8) geomean 1.756Gi 1.765Gi +0.50%

Jake Bailey (jakebailey) · 2026-10-19T17:46:44Z

TypeScript Bot (@typescript-bot) perf test this faster

typescript-automation · 2026-10-19T17:46:50Z

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
`perf test this faster`	✅ Started	👀 Results

Copilot

🟢 Approval recommended

The migration consistently reuses the existing store implementation, with no blocking issues identified.

No open issues 🎉

What changed in this PR

Replaces the checker’s remaining map-backed symbol links with existing ID-indexed paged stores to reduce lookup overhead.

Changes:

Migrates all remaining symbol-link stores to symbolLinkStore.
Renames the reverse-mapped store and updates its callers.

File	Description
tsc/internal/checker/nodebuilderimpl.go	Updates reverse-mapped store references.
tsc/internal/checker/inference.go	Updates reverse-mapped link access.
tsc/internal/checker/emitsupport.go	Updates reverse-mapped lookup during emit.
tsc/internal/checker/checker.go	Converts remaining symbol-link stores to paged storage.

_{Review effort: Balanced}

typescript-automation · 2026-10-19T18:24:28Z

Jake Bailey (@jakebailey)
The results of the perf run you requested are in!

Here they are:

tsc

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{Compiler-Unions - native}
_Errors	₄₁	₄₁	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_115,276	_115,276	_~	_~	_~	_{p=1.000 n=12}
_Types	_79,613	_79,613	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{113,504k (± 0.07%)}	_{116,422k (± 0.07%)}	_{+2,918k (+ 2.57%)}	_116,260k	_116,742k	_{p=0.000 n=12}
_{Memory Allocs}	_{2,212,539 (± 0.01%)}	_{2,213,871 (± 0.01%)}	_{+1,332 (+ 0.06%)}	_2,213,420	_2,214,176	_{p=0.000 n=12}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.048s (± 4.42%)}	_{0.048s (± 4.24%)}	_~	_0.043s	_0.052s	_{p=0.759 n=12}
_{Bind Time}	_{0.017s (± 9.74%)}	_{0.017s (±10.11%)}	_~	_0.013s	_0.021s	_{p=0.856 n=12}
_{Check Time}	_{0.566s (± 1.02%)}	_{0.560s (± 0.74%)}	_~	_0.552s	_0.573s	_{p=0.057 n=12}
_{Emit Time}	_{0.327s (± 3.20%)}	_{0.325s (± 2.41%)}	_~	_0.306s	_0.345s	_{p=0.766 n=12}
_{Total Time}	_{0.967s (± 1.04%)}	_{0.958s (± 0.79%)}	_~	_0.940s	_0.980s	_{p=0.139 n=12}
_{angular-1 - native}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_{846,750 (± 0.07%)}	_{846,918 (± 0.11%)}	_~	_844,123	_848,753	_{p=0.671 n=12}
_Types	_{247,033 (± 0.00%)}	_{247,032 (± 0.00%)}	_~	_247,030	_247,040	_{p=0.128 n=12}
_{Memory Used}	_{596,235k (± 0.02%)}	_{610,468k (± 0.02%)}	_{+14,233k (+ 2.39%)}	_610,157k	_610,880k	_{p=0.000 n=12}
_{Memory Allocs}	_{13,150,380 (± 0.10%)}	_{13,150,732 (± 0.04%)}	_~	_13,143,369	_13,166,383	_{p=0.078 n=12}
_{Config Time}	_{0.020s (± 1.21%)}	_{0.020s (± 1.21%)}	_~	_0.020s	_0.021s	_{p=1.000 n=12}
_{Parse Time}	_{0.281s (± 1.83%)}	_{0.284s (± 2.91%)}	_~	_0.267s	_0.310s	_{p=0.745 n=12}
_{Bind Time}	_{0.100s (±13.47%)}	_{0.109s (±13.79%)}	_~	_0.072s	_0.142s	_{p=0.433 n=12}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=12}
_{Emit Time}	_{1.857s (± 1.73%)}	_{1.853s (± 1.22%)}	_~	_1.801s	_1.902s	_{p=0.856 n=12}
_{Total Time}	_{2.279s (± 1.53%)}	_{2.288s (± 1.17%)}	_~	_2.217s	_2.334s	_{p=0.755 n=12}
_{mui-docs - native}
_Errors	_11,405	_11,405	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_4,331,983	_4,331,983	_~	_~	_~	_{p=1.000 n=12}
_Types	_1,370,520	_1,370,520	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{2,623,124k (± 0.05%)}	_{2,621,707k (± 0.04%)}	_~	_2,618,717k	_2,625,807k	_{p=0.114 n=12}
_{Memory Allocs}	_{27,698,596 (± 0.09%)}	_{27,713,426 (± 0.08%)}	_~	_27,638,158	_27,782,235	_{p=0.078 n=12}
_{Config Time}	_{0.020s (± 1.60%)}	_{0.020s (± 1.59%)}	_~	_0.020s	_0.021s	_{p=1.000 n=12}
_{Parse Time}	_{0.585s (± 2.33%)}	_{0.580s (± 2.00%)}	_~	_0.533s	_0.600s	_{p=0.943 n=12}
_{Bind Time}	_{0.003s (±10.34%)}	_{0.003s (±23.37%)}	_~	_0.002s	_0.006s	_{p=1.000 n=12}
_{Check Time}	_{8.658s (± 0.56%)}	_{8.474s (± 0.20%)}	_{-0.184s (- 2.12%)}	_8.403s	_8.516s	_{p=0.000 n=12}
_{Emit Time}	_{0.673s (±11.75%)}	_{0.677s (±10.62%)}	_~	_0.499s	_0.793s	_{p=0.682 n=12}
_{Total Time}	_{10.875s (± 0.77%)}	_{10.699s (± 0.69%)}	_{-0.176s (- 1.62%)}	_10.476s	_10.806s	_{p=0.006 n=12}
_{strada-build-src - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,388,680	_1,388,680	_~	_~	_~	_{p=1.000 n=12}
_Types	_441,862	_441,862	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{1,311,668k (± 0.76%)}	_{1,365,141k (± 0.44%)}	_{🔻+53,473k (+ 4.08%)}	_1,348,695k	_1,383,809k	_{p=0.000 n=12}
_{Memory Allocs}	_{78,181,622 (± 0.16%)}	_{78,292,707 (± 0.08%)}	_~	_78,073,114	_78,416,940	_{p=0.242 n=12}
_{Config Time}	_{0.005s (±10.88%)}	_{0.004s (±12.82%)}	_~	_0.003s	_0.006s	_{p=0.735 n=12}
_{Parse Time}	_{0.311s (± 1.95%)}	_{0.308s (± 2.31%)}	_~	_0.290s	_0.327s	_{p=0.579 n=12}
_{Bind Time}	_0.000s	_{0.000s (±217.90%)}	_~	_0.000s	_0.001s	_{p=1.000 n=12}
_{Check Time}	_{1.996s (± 0.57%)}	_{2.005s (± 0.59%)}	_~	_1.976s	_2.032s	_{p=0.183 n=12}
_{Emit Time}	_{0.354s (± 3.13%)}	_{0.348s (± 2.57%)}	_~	_0.328s	_0.381s	_{p=0.224 n=12}
_{Total Time}	_{23.745s (± 0.32%)}	_{23.768s (± 0.58%)}	_~	_23.362s	_24.059s	_{p=0.671 n=12}
_{strada-compiler - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_334,953	_334,953	_~	_~	_~	_{p=1.000 n=12}
_Types	_197,616	_197,616	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{247,545k (± 0.03%)}	_{254,943k (± 0.04%)}	_{+7,398k (+ 2.99%)}	_254,650k	_255,128k	_{p=0.000 n=12}
_{Memory Allocs}	_{4,329,829 (± 0.01%)}	_{4,332,920 (± 0.01%)}	_{+3,091 (+ 0.07%)}	_4,332,173	_4,334,014	_{p=0.000 n=12}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.108s (± 3.12%)}	_{0.112s (± 5.44%)}	_~	_0.095s	_0.129s	_{p=0.224 n=12}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{0.960s (± 0.66%)}	_{0.951s (± 0.57%)}	_~	_0.939s	_0.965s	_{p=0.071 n=12}
_{Emit Time}	_{0.153s (± 6.45%)}	_{0.154s (± 4.73%)}	_~	_0.139s	_0.178s	_{p=0.831 n=12}
_{Total Time}	_{1.276s (± 0.72%)}	_{1.275s (± 0.75%)}	_~	_1.254s	_1.300s	_{p=0.832 n=12}
_{ts-pre-modules - native}
_Errors	₈₇	₈₇	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_303,834	_303,834	_~	_~	_~	_{p=1.000 n=12}
_Types	_181,663	_181,663	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{215,258k (± 0.02%)}	_{221,610k (± 0.02%)}	_{+6,352k (+ 2.95%)}	_221,482k	_221,707k	_{p=0.000 n=12}
_{Memory Allocs}	_{1,401,702 (± 0.02%)}	_{1,404,753 (± 0.02%)}	_{+3,051 (+ 0.22%)}	_1,404,205	_1,405,177	_{p=0.000 n=12}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.078s (± 4.45%)}	_{0.077s (± 3.54%)}	_~	_0.067s	_0.083s	_{p=0.876 n=12}
_{Bind Time}	_{0.034s (± 8.08%)}	_{0.033s (± 9.81%)}	_~	_0.024s	_0.042s	_{p=0.853 n=12}
_{Check Time}	_{0.618s (± 0.91%)}	_{0.616s (± 1.18%)}	_~	_0.604s	_0.638s	_{p=0.369 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{0.742s (± 0.65%)}	_{0.738s (± 0.72%)}	_~	_0.726s	_0.756s	_{p=0.297 n=12}
_{vscode - native}
_Errors	₃₉₆	₃₉₆	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_12,386,876	_12,386,876	_~	_~	_~	_{p=1.000 n=12}
_Types	_4,049,733	_4,049,733	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{5,821,013k (± 0.01%)}	_{6,036,307k (± 0.01%)}	_{+215,294k (+ 3.70%)}	_6,034,005k	_6,038,067k	_{p=0.000 n=12}
_{Memory Allocs}	_{59,187,953 (± 0.01%)}	_{59,292,258 (± 0.02%)}	_{+104,305 (+ 0.18%)}	_59,279,296	_59,331,163	_{p=0.000 n=12}
_{Config Time}	_{0.077s (± 0.53%)}	_{0.076s (± 0.43%)}	_~	_0.075s	_0.077s	_{p=0.051 n=12}
_{Parse Time}	_{1.811s (± 1.95%)}	_{1.815s (± 2.28%)}	_~	_1.719s	_1.934s	_{p=0.899 n=12}
_{Bind Time}	_{0.700s (±11.97%)}	_{0.698s (±12.55%)}	_~	_0.519s	_0.930s	_{p=0.887 n=12}
_{Check Time}	_{15.559s (± 0.90%)}	_{15.435s (± 0.97%)}	_~	_15.085s	_15.768s	_{p=0.599 n=12}
_{Emit Time}	_{5.740s (± 6.99%)}	_{5.237s (± 7.71%)}	_~	_4.563s	_6.230s	_{p=0.101 n=12}
_{Total Time}	_{23.982s (± 1.31%)}	_{23.353s (± 1.46%)}	_{-0.629s (- 2.62%)}	_22.754s	_24.217s	_{p=0.010 n=12}
_{webpack - native}
_Errors	₅₉₈	₅₉₈	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,398,302	_1,398,302	_~	_~	_~	_{p=1.000 n=12}
_Types	_670,900	_670,900	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{885,743k (± 0.02%)}	_{901,174k (± 0.01%)}	_{+15,431k (+ 1.74%)}	_900,756k	_901,468k	_{p=0.000 n=12}
_{Memory Allocs}	_{6,927,047 (± 0.02%)}	_{6,933,691 (± 0.01%)}	_{+6,645 (+ 0.10%)}	_6,932,285	_6,935,472	_{p=0.000 n=12}
_{Config Time}	_0.009s	_0.009s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.316s (± 3.02%)}	_{0.319s (± 3.79%)}	_~	_0.289s	_0.347s	_{p=0.701 n=12}
_{Bind Time}	_{0.077s (± 4.32%)}	_{0.080s (±14.26%)}	_~	_0.071s	_0.137s	_{p=0.478 n=12}
_{Check Time}	_{2.964s (± 0.24%)}	_{2.920s (± 0.41%)}	_{-0.043s (- 1.46%)}	_2.875s	_2.963s	_{p=0.000 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{3.402s (± 0.32%)}	_{3.365s (± 0.40%)}	_{-0.037s (- 1.09%)}	_3.331s	_3.399s	_{p=0.000 n=12}
_{xstate-main - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,060,810	_1,060,810	_~	_~	_~	_{p=1.000 n=12}
_Types	_389,671	_389,671	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{471,725k (± 0.02%)}	_{487,105k (± 0.03%)}	_{+15,380k (+ 3.26%)}	_486,824k	_487,440k	_{p=0.000 n=12}
_{Memory Allocs}	_{4,218,847 (± 0.07%)}	_{4,227,523 (± 0.09%)}	_{+8,676 (+ 0.21%)}	_4,219,900	_4,238,220	_{p=0.000 n=12}
_{Config Time}	_{0.003s (±11.61%)}	_{0.003s (± 6.23%)}	_~	_0.002s	_0.003s	_{p=0.317 n=12}
_{Parse Time}	_{0.135s (± 2.99%)}	_{0.134s (± 3.91%)}	_~	_0.125s	_0.151s	_{p=0.680 n=12}
_{Bind Time}	_{0.045s (±18.15%)}	_{0.048s (±14.71%)}	_~	_0.034s	_0.068s	_{p=0.465 n=12}
_{Check Time}	_{1.103s (± 1.20%)}	_{1.083s (± 0.60%)}	_{-0.020s (- 1.81%)}	_1.063s	_1.095s	_{p=0.009 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{1.291s (± 0.95%)}	_{1.276s (± 0.80%)}	_{-0.016s (- 1.22%)}	_1.246s	_1.294s	_{p=0.043 n=12}

System info unknown

Hosts

native

Scenarios

Compiler-Unions - native
angular-1 - native
mui-docs - native
strada-build-src - native
strada-compiler - native
ts-pre-modules - native
vscode - native
webpack - native
xstate-main - native

_Benchmark	_Name	_Iterations
_Current	_pr	₁₂
_Baseline	_baseline	₁₂

Developer Information:

Download Benchmarks

Copilot AI balanced review requested due to automatic review settings October 19, 2026 17:46

github-project-automation Bot added this to PR Backlog Oct 19, 2026

typescript-automation Bot assigned Jake Bailey (jakebailey) Oct 19, 2026

typescript-automation Bot added the Author: Team label Oct 19, 2026

github-project-automation Bot moved this to Not started in PR Backlog Oct 19, 2026

typescript-automation Bot added the For Uncommitted Bug PR for untriaged, rejected, closed or missing bug label Oct 19, 2026

Copilot started reviewing on behalf of Jake Bailey (jakebailey) October 19, 2026 17:47

View session

Copilot AI reviewed Oct 19, 2026

View reviewed changes

Navigation Menu

Repository navigation

Use paged link stores for all symbol links - #64872

Use paged link stores for all symbol links#64872
Jake Bailey (jakebailey) wants to merge 1 commit into
microsoft:mainfrom
jakebailey:perf/paged-symbol-links

Jake Bailey (jakebailey) commented Oct 19, 2026

Uh oh!

Jake Bailey (jakebailey) commented Oct 19, 2026

Uh oh!

typescript-automation Bot commented Oct 19, 2026 •

edited

Loading

Uh oh!

Copilot AI left a comment

Uh oh!

typescript-automation Bot commented Oct 19, 2026

tsc

Uh oh!

This branch has not been deployed

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Conversation

Jake Bailey (jakebailey) commented Oct 19, 2026

Uh oh!

Jake Bailey (jakebailey) commented Oct 19, 2026

Uh oh!

typescript-automation Bot commented Oct 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

🟢 Approval recommended

Uh oh!

typescript-automation Bot commented Oct 19, 2026

tsc

Uh oh!

This branch has not been deployed

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

typescript-automation Bot commented Oct 19, 2026 •

edited

Loading