diff --git a/ci/Dockerfile b/ci/Dockerfile
index 57c8e72..53a5504 100755
--- a/ci/Dockerfile
+++ b/ci/Dockerfile
@@ -48,9 +48,9 @@ RUN --mount=type=secret,id=gitea_token \
 #-----------------------------------------------------------------------
 WORKDIR /opt/moos-ivp
 
-RUN ./build-moos.sh -m -j"$(nproc)" && \
+RUN ./build-moos.sh -m -j2 && \
     make -C build/MOOS/MOOSCore install && \
-    ./build-ivp.sh -n -j"$(nproc)" && \
+    ./build-ivp.sh -n -j2 && \
     make -C build/ivp install && \
     ldconfig
 
@@ -75,7 +75,7 @@ RUN --mount=type=secret,id=gitea_token \
     git clone --depth 1 "https://zjk:${TOKEN}@gitea2.zhaojingkui.xyz/zjk/googletest.git" /opt/googletest; \
     mkdir -p /opt/googletest/build && cd /opt/googletest/build && \
     cmake -DCMAKE_BUILD_TYPE=Release -DBUILD_GMOCK=ON .. && \
-    make -j"$(nproc)" && \
+    make -j2 && \
     make install && \
     ldconfig
 
diff --git a/ci/build-test.sh b/ci/build-test.sh
index be79288..bc3b79a 100755
--- a/ci/build-test.sh
+++ b/ci/build-test.sh
@@ -40,7 +40,7 @@ mkdir -p build
 cd build
 t0=$(now_ms)
 if cmake -DCMAKE_BUILD_TYPE=Release .. > /tmp/cmake.log 2>&1 \
-   && make -j"$(nproc)" > /tmp/make.log 2>&1; then
+   && make -j2 > /tmp/make.log 2>&1; then
     BUILD_OK=1
 else
     echo "--- build failed ---" >&2
@@ -92,6 +92,8 @@ fi
 #-----------------------------------------------------------------------
 if [ "${BUILD_OK}" = "1" ]; then
     echo ">>> Smoke test: launch MOOSDB + pPowerManger"
+    echo ">>> [mem-diagnostic] nproc=$(nproc), ulimit -v=$(ulimit -v), free:" 
+    free -m 2>/dev/null | head -3 || true
 
     MOOSDB="$(command -v MOOSDB || true)"
     if [ -z "${MOOSDB}" ]; then