Precompile never stops with v 2.0.0?

[colbec]

I see that there has been a major upgrade to 2.0.0. I'm on Julia 1.12.6 and HTTP takes an inordinately long time to precompile. No error messages are generated. I need to get an application up and running so I went back to julia 1.12.5 and HTTP 1.11 and everything is working so no problems.

Since the precompile process is quite silent, I wonder if there is a way to increase the verbosity of the process to verify that progress is actually under way? Admittedly this is a big jump and it might be that my application demands are getting too loud.

[colbec]

I discovered that pressing 'v' while the precompile is in progtess should provide feedback on the machine state as the precompile proceeds. However when I press 'v' no output is generated.

For further info I am running Fedora 44 fully updated.

[quinnj]

Thanks for the report! Precompile workload in 2.0 is much more extensive that previous versions. A couple of things to try/report on:

You can disable precompilation entirely by doing:

using Preferences
set_preferences!("HTTP", "precompile_workload" => false; force=true)

that can at least be an escape hatch for you and more precisely help us know that it is indeed the precompilation workload that is hanging.

Also, how long did you let it run? As I mentioned, it's definitely more extensive than previous versions, and possible it's hitting some extreme compiler case or something where it's technically working, but takes forever.

Can you share the result of versioninfo() and JULIA_NUM_THREADS please?

also if you know of any firewall, SELinux, or ipv6 restrictions or things that may affect localhost serving/callbacks?

[colbec]

Here is version info:

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: 4 × Intel(R) Core(TM) i5-4460  CPU @ 3.20GHz
  WORD_SIZE: 64
  LLVM: libLLVM-18.1.7 (ORCJIT, haswell)
  GC: Built with stock GC
Threads: 1 default, 1 interactive, 1 GC (on 4 virtual cores)

JULIA_NUM_THREADS was not defined for my first attempts, so default values.

The longest I let it run was about 20 minutes.

julia --threads=4
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.12.6 (2026-04-09)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org release
|__/                   |

julia> using Preferences
 │ Package Preferences not found, but a package named Preferences is available from a registry. 
 │ Install package?
 │   (@v1.12) pkg> add Preferences 
 └ (y/n/o) [y]: y
   Resolving package versions...
    Updating `~/.julia/environments/v1.12/Project.toml`
  [21216c6a] + Preferences v1.5.2
    Manifest No packages added to or removed from `~/.julia/environments/v1.12/Manifest.toml`

julia> set_preferences!("HTTP", "precompile_workload" => false; force=true)

(@v1.12) pkg> status HTTP
Status `~/.julia/environments/v1.12/Project.toml`
  [cd3eb016] HTTP v2.0.0

julia> using HTTP
[ Info: Precompiling HTTP [cd3eb016-35fb-5094-929b-558a96fad6f3](cache misses: incompatible header (1), dep missing source (1))
Precompiling packages  ╺━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 0/1
(..spinner..) HTTP Being precompiled by another process (pid: 27395, pidfile: /home/colin/.julia/com…

Process 27395 looks entirely normal.
Processor: Intel® Core™ i5-4460 × 4

Still no response from 'v' at the keyboard to trigger progress report.

The spinner is still twiddling away after 15 minutes so I will let it run for a bit and post back with result.

===
Update:
Two hours later still no response. Giving up.

^C Interrupted: Exiting precompilation...
[ Info: Waiting for another process (pid: 27395) to finish precompiling HTTP [cd3eb016-35fb-5094-929b-558a96fad6f3]. Pidfile: /home/colin/.julia/compiled/v1.12/HTTP/zXWya_Cc45j.ji.pidfile

[colbec]

Is there a straightforward way to test whether my localhost is set up according to the requirements in this case? I am not aware of anything which might block the process. My OS is fully up to datebut there might be something I need to install, but what might that be? Applications that require a secure connection don't seem to have a problem. However I am not aware of anything using ipv6 for example.

[zgornel]

I have the same issue, on julia v1.12.6, v1.14.0-DEV.2136 and v1.14.0-DEV.2265. Looks like precompilation hangs somewhere, no CPU being used by the process itself.