perf(web): reuse incremental build and status caches

tools/web/build-blender-native.sh

@@ -6,7 +6,7 @@ repo_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
 source "${repo_root}/tools/web/native-build-env.sh"
 
 build_target="${BLENDER_BUILD_TARGET:-blender}"
-jobs="${BLENDER_BUILD_JOBS:-2}"
+jobs="${BLENDER_BUILD_JOBS:-$(WEB_BUILD_MEMORY_GIB_PER_JOB=6 WEB_BUILD_JOBS_CAP=12 bash "${repo_root}/tools/web/compute-build-jobs.sh")}"
 cmake --build "${BLENDER_BUILD_DIR}" --target "${build_target}" --parallel "${jobs}"
 test -x "${BLENDER_BUILD_DIR}/bin/blender"
 

tools/web/build-web-engine-variants.sh

@@ -8,9 +8,18 @@ configure_variant() {
   local name="$1"
   local threads="$2"
   local build_dir="${repo_root}/build_web-${name}"
-  emcmake cmake --fresh -S "${repo_root}/web/engine" -B "${build_dir}" -G Ninja \
-    -DCMAKE_BUILD_TYPE=Release -DWEB_ENGINE_THREADS="${threads}"
-  cmake --build "${build_dir}" --target web_engine
+  local configure_args=(
+    -S "${repo_root}/web/engine"
+    -B "${build_dir}"
+    -G Ninja
+    -DCMAKE_BUILD_TYPE=Release
+    -DWEB_ENGINE_THREADS="${threads}"
+  )
+  if [[ "${WEB_ENGINE_FORCE_RECONFIGURE:-0}" == "1" ]]; then
+    configure_args=(--fresh "${configure_args[@]}")
+  fi
+  emcmake cmake "${configure_args[@]}"
+  cmake --build "${build_dir}" --target web_engine --parallel "${WEB_BUILD_JOBS:-$(bash "${repo_root}/tools/web/compute-build-jobs.sh")}"
   test -s "${build_dir}/web_engine.js"
   test -s "${build_dir}/web_engine.wasm"
   printf '%s variant ok: %s\n' "${name}" "${build_dir}"

tools/web/compute-build-jobs.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Choose a high-throughput but memory-safe default. Callers can override with
+# WEB_BUILD_JOBS; the per-job memory estimate keeps large Blender/Emscripten
+# links from swapping while still using more than the historical -j8 default
+# on hosts with enough RAM.
+if [[ -n "${WEB_BUILD_JOBS:-}" ]]; then
+  printf '%s\n' "${WEB_BUILD_JOBS}"
+  exit 0
+fi
+
+cpu_count="$(getconf _NPROCESSORS_ONLN 2>/dev/null || printf '8')"
+memory_kib="$(awk '/MemAvailable:/ { print $2; exit }' /proc/meminfo 2>/dev/null || printf '0')"
+memory_per_job_gib="${WEB_BUILD_MEMORY_GIB_PER_JOB:-4}"
+job_cap="${WEB_BUILD_JOBS_CAP:-16}"
+
+if [[ ! "${cpu_count}" =~ ^[0-9]+$ ]] || ((cpu_count < 1)); then cpu_count=8; fi
+if [[ ! "${memory_kib}" =~ ^[0-9]+$ ]] || ((memory_kib < 1)); then memory_kib=$((8 * 1024 * 1024)); fi
+if [[ ! "${memory_per_job_gib}" =~ ^[0-9]+$ ]] || ((memory_per_job_gib < 1)); then memory_per_job_gib=4; fi
+if [[ ! "${job_cap}" =~ ^[0-9]+$ ]] || ((job_cap < 1)); then job_cap=16; fi
+
+memory_jobs=$((memory_kib / (memory_per_job_gib * 1024 * 1024)))
+if ((memory_jobs < 2)); then memory_jobs=2; fi
+jobs=$cpu_count
+if ((jobs > memory_jobs)); then jobs=$memory_jobs; fi
+if ((jobs > job_cap)); then jobs=$job_cap; fi
+if ((jobs < 2)); then jobs=2; fi
+printf '%s\n' "${jobs}"

tools/web/emscripten-env.sh

@@ -40,8 +40,10 @@ if [[ -d /dev/shm && -w /dev/shm ]]; then
 else
   export EM_CACHE="${EM_CACHE-${web_workspace_root}/.emcache}"
 fi
-export CMAKE_BUILD_PARALLEL_LEVEL="${CMAKE_BUILD_PARALLEL_LEVEL-8}"
-export NINJAFLAGS="${NINJAFLAGS--j8}"
+web_build_jobs="$(WEB_BUILD_MEMORY_GIB_PER_JOB=4 WEB_BUILD_JOBS_CAP=16 bash "${web_workspace_root}/tools/web/compute-build-jobs.sh")"
+export WEB_BUILD_JOBS="${WEB_BUILD_JOBS-${web_build_jobs}}"
+export CMAKE_BUILD_PARALLEL_LEVEL="${CMAKE_BUILD_PARALLEL_LEVEL-${WEB_BUILD_JOBS}}"
+export NINJAFLAGS="${NINJAFLAGS--j${WEB_BUILD_JOBS}}"
 export WEB_EMSCRIPTEN_CFLAGS="-sENVIRONMENT=web,worker -sMODULARIZE=1 -sEXPORT_ES6=1"
 export WEB_EMSCRIPTEN_LDFLAGS="-sALLOW_MEMORY_GROWTH=1 -sFILESYSTEM=1"