From d493ae2c196983d2e879c7aeec58f1ec2c6dda34 Mon Sep 17 00:00:00 2001
From: Jason Garber <jason.garber@cargosense.com>
Date: Mon, 16 Mar 2026 15:21:14 +0000
Subject: [PATCH] Add parallel dependency compilation env variable

Projects using this Feature will benefit from the recommended setting
of this new environment variable to half the available CPUs (see link
below).

See-also: https://elixir-lang.org/blog/2025/10/16/elixir-v1-19-0-released/#parallel-compilation-of-dependencies
---
 src/elixir-project/devcontainer-feature.json  | 2 +-
 src/elixir-project/scripts/onCreateCommand.sh | 4 +++-
 test/elixir-project/test.sh                   | 2 +-
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/elixir-project/devcontainer-feature.json b/src/elixir-project/devcontainer-feature.json
index ecff31e..82ed8d1 100644
--- a/src/elixir-project/devcontainer-feature.json
+++ b/src/elixir-project/devcontainer-feature.json
@@ -1,6 +1,6 @@
 {
   "id": "elixir-project",
-  "version": "1.0.0",
+  "version": "1.1.0",
   "name": "elixir-project",
   "description": "An opinionated, batteries-included Dev Container Feature for Elixir projects.",
   "documentationURL": "https://github.com/CargoSense/devcontainer-features/tree/main/src/elixir-project",
diff --git a/src/elixir-project/scripts/onCreateCommand.sh b/src/elixir-project/scripts/onCreateCommand.sh
index 14e3965..5230bbb 100755
--- a/src/elixir-project/scripts/onCreateCommand.sh
+++ b/src/elixir-project/scripts/onCreateCommand.sh
@@ -11,10 +11,12 @@ BASHRC_DIR="${HOME}/.bashrc.d"
 mkdir -p "${BASHRC_DIR}"
 chmod 700 "${BASHRC_DIR}"
 
-# Configure environment variables that rely on `CONTAINER_WORKSPACE_FOLDER`
+# Configure environment variables that rely on `CONTAINER_WORKSPACE_FOLDER` and
+# set dependency compilation parallelism (new in Elixir v1.19)
 cat << EOF > "${BASHRC_DIR}/elixir-project.bashrc"
 export HISTFILE="${CONTAINER_WORKSPACE_FOLDER}/.bash_history"
 export ERL_AFLAGS="-kernel shell_history enabled -kernel shell_history_path '\\"${CONTAINER_WORKSPACE_FOLDER}/.iex_history\\"'"
+export MIX_OS_DEPS_COMPILE_PARTITION_COUNT="\$(( "\$(nproc --all)" / 2 ))"
 EOF
 
 chmod +x "${BASHRC_DIR}/elixir-project.bashrc"
diff --git a/test/elixir-project/test.sh b/test/elixir-project/test.sh
index a458bad..60d1e5d 100755
--- a/test/elixir-project/test.sh
+++ b/test/elixir-project/test.sh
@@ -7,7 +7,7 @@ set -e
 source dev-container-features-test-lib
 
 # Feature-specific tests
-check "environment" bash -c "env | grep ERL_AFLAGS"
+check "environment" bash -c "env | grep ERL_AFLAGS && env | grep MIX_OS_DEPS_COMPILE_PARTITION_COUNT"
 check "gitignore" grep -xF .bash_history .gitignore
 
 # Report result