feat(core): use jemalloc with tuned decay timers for native module

[leosvelperez]

Current Behavior

The Nx native module (Rust cdylib loaded by Node.js) uses the system allocator. The daemon process retains a large RSS footprint after the initial project graph build, even though most of that memory is no longer in use. On macOS and Linux, the system allocator doesn't aggressively return freed pages to the OS.

Expected Behavior

The daemon's steady-state RSS drops significantly after graph build by using jemalloc with tuned page purge timers. Peak RSS and wall time are unaffected.

Changes

Adds tikv-jemallocator as the global allocator on Linux and macOS, with two compile-time settings:

• dirty_decay_ms:1000 — returns freed pages to the OS after 1s instead of the default 10s. Tuned to Nx's phase-separated workload (graph build → idle → task execution), where transitions happen every ~30-60s. Benchmarked against 5s and 10s — both too slow to purge between phases.
• muzzy_decay_ms:0 — skips the lazy purge phase (MADV_FREE) and goes straight to MADV_DONTNEED. Required on macOS and Linux ≥ 4.5 where MADV_FREE doesn't actually reduce RSS.

Windows and WASI continue using the system allocator. Windows is excluded because tikv-jemalloc-sys fails to build with MSVC (spaces in cl.exe path break the autoconf configure script). Tracked upstream in tikv/jemallocator#99.

Other Settings Considered

Tested narenas reduction, tcache_max, extent fit tuning, background threads, and decay timer values. Only the decay timer configuration improved steady-state RSS without wall time regression.

[netlify]

✅ Deploy Preview for nx-dev ready!

Name	Link
🔨 Latest commit	647ee9d
🔍 Latest deploy log	https://app.netlify.com/projects/nx-dev/deploys/6998acddc1b37800082a9e21
😎 Deploy Preview	https://deploy-preview-34444--nx-dev.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[netlify]

✅ Deploy Preview for nx-docs ready!

Name	Link
🔨 Latest commit	647ee9d
🔍 Latest deploy log	https://app.netlify.com/projects/nx-docs/deploys/6998acdd75c0db0008875704
😎 Deploy Preview	https://deploy-preview-34444--nx-docs.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[nx-cloud]

View your CI Pipeline Execution ↗ for commit 647ee9d

Command	Status	Duration	Result
nx affected --targets=lint,test,test-kt,build,e...	⛔ Cancelled	1h 39m 59s	View ↗
nx run-many -t check-imports check-lock-files c...	✅ Succeeded	3m 6s	View ↗
nx-cloud record -- nx-cloud conformance:check	✅ Succeeded	8s	View ↗
nx-cloud record -- nx format:check	✅ Succeeded	<1s	View ↗
nx-cloud record -- nx sync:check	✅ Succeeded	<1s	View ↗

---

☁️ Nx Cloud last updated this comment at 2026-02-20 20:45:10 UTC

[github-actions]

Failed to publish a PR release of this pull request, triggered by @leosvelperez.
See the failed workflow run at: https://github.com/nrwl/nx/actions/runs/21994871776

[github-actions]

Failed to publish a PR release of this pull request, triggered by @leosvelperez.
See the failed workflow run at: https://github.com/nrwl/nx/actions/runs/22056708532

[nx-cloud]

Nx Cloud is proposing a fix for your failed CI:

These changes adjust the jemalloc configuration to fix Gradle daemon termination failures in e2e tests. The original muzzy_decay_ms:0 setting was too aggressive, causing immediate memory unmapping via MADV_DONTNEED that interfered with Node.js process coordination when managing multiple Gradle daemon subprocesses. Setting muzzy_decay_ms:1000 maintains the memory reduction benefits while allowing a brief delay before aggressive unmapping, preventing interference with concurrent process management and signal handling.

Tip

✅ We verified this fix by re-running e2e-gradle:e2e-ci--src/gradle-plugin-v1.test.ts.

diff --git a/.cargo/config.toml b/.cargo/config.toml
index 2e9a2981dd..93c18852e5 100644
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -1,5 +1,5 @@
 [env]
-JEMALLOC_SYS_WITH_MALLOC_CONF = "dirty_decay_ms:1000,muzzy_decay_ms:0"
+JEMALLOC_SYS_WITH_MALLOC_CONF = "dirty_decay_ms:1000,muzzy_decay_ms:1000"
 
 [build]
 target-dir = 'dist/target'

  

Or Apply changes locally with:

npx nx-cloud apply-locally 85eG-u8ne

Apply fix locally with your editor ↗   View interactive diff ↗

_{🎓 Learn more about Self-Healing CI on nx.dev}