[Crystal] Process fork is unsupported with multithreaded mode

Author: waghanzaCreated Aug 19, 2026Updated Aug 19, 2026

Hi, @Blacksmoke16 @grkek @jwoertink,

Could you take a look @ https://github.com/the-benchmarker/web-frameworks/blob/d6532eed7d41adff7b178b514fb1c47bed3513f2/crystal/athena/src/server.cr#L21

please ?

I have

bash

4.799 In src/server.cr:21:11
4.799
4.799  21 | Process.fork do
4.799               ^---
4.799 Error: Process fork is unsupported with multithreaded mode
4.799
------
.Dockerfile.default:19
--------------------
  18 |
  19 | >>> RUN --mount=type=cache,id=shards-lib-1.21,target=lib \
  20 | >>>   shards build --release --no-debug
  21 |
--------------------
ERROR: failed to build: failed to solve: process "/bin/sh -c shards build --release --no-debug" did not complete successfully: exit code: 1

and I can not update some crystal frameworks in https://github.com/the-benchmarker/web-frameworks/pull/9648

Source: the-benchmarker/web-frameworks

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