# Multi-threaded compilation of project packages hang, works after Julia restart

**URL:** https://discourse.julialang.org/t/multi-threaded-compilation-of-project-packages-hang-works-after-julia-restart/137226
**Category:** Internals & Design
**Created:** [May 21, 2026, 4:46pm UTC](https://discourse.julialang.org/t/multi-threaded-compilation-of-project-packages-hang-works-after-julia-restart/137226 "2026-05-21T16:46:52Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![sob](https://avatars.discourse-cdn.com/v4/letter/s/65b543/32.png) [@sob](https://discourse.julialang.org/u/sob)
#### Post date: [May 21, 2026, 4:46pm UTC](https://discourse.julialang.org/t/multi-threaded-compilation-of-project-packages-hang-works-after-julia-restart/137226/1 "2026-05-21T16:46:52Z")

</div>

I’m running Julia 1.12

```julia-auto
julia> versioninfo()
Julia Version 1.12.6
Commit 15346901f00 (2026-04-09 19:20 UTC)
Build Info:
  Official https://julialang.org release
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 128 × AMD Ryzen Threadripper PRO 9985WX 64-Cores
  WORD_SIZE: 64
  LLVM: libLLVM-18.1.7 (ORCJIT, znver5)
  GC: Built with stock GC
Threads: 128 default, 1 interactive, 128 GC (on 128 virtual cores)
Environment:
  JULIA_NUM_THREADS = auto

```

As I was debugging a rather large project, I think I ended up in an state that more or less required me to remove `.julia/compiled/v1.12`.

When running `precompile` on my project, the REPL seemed to run indefinitely while compiling `OrdinaryDiffEqVerner`, which was package 705/711. After 30 minutes, I decided to kill it, restart and recompile, and my remaining 6 packages compiled immediately.

I’m curious to know how this can happen? I imagine this is not necessarily related to this specific package, but are we in a situation where race conditions can arise during precompilation?