message: Change to using `nproc` to detect CPU_CORES.
diff: # If you have runtime memory issues, disable tcmalloc: add -DNO_TCMALLOC to the make line
  +ifeq ($(CPU_CORES),)
  +CPU_CORES := $(shell nproc)
  +ifeq ($(CPU_CORES),)
  +CPU_CORES := 1
  +endif
  +endif
  +
  PREFIX ?= /usr/local
  release:
  @@ -28,11 +35,11 @@ test/regression:
  test: test/unittest test/regression
  test-parallel: test/unittest
  - mkdir -p build/tests; cd build; rm -rf test; mkdir test; cd test; ../../tests/cmake_gen.tcl; cmake .; make -j 4; cd ..; ../tests/regression.tcl diff_mode show_diff;
  + mkdir -p build/tests; cd build; rm -rf test; mkdir test; cd test; ../../tests/cmake_gen.tcl; cmake .; make -j $(CPU_CORES); cd ..; ../tests/regression.tcl diff_mode show_diff;
  # mkdir -p build/tests; cd build; ../tests/regression.tcl mt=2 show_diff
  regression:
  - mkdir -p build/tests; cd build; rm -rf test; mkdir test; cd test; ../../tests/cmake_gen.tcl; cmake .; make -j 24; cd ..; ../tests/regression.tcl diff_mode show_diff;
  + mkdir -p build/tests; cd build; rm -rf test; mkdir test; cd test; ../../tests/cmake_gen.tcl; cmake .; make -j $(CPU_CORES); cd ..; ../tests/regression.tcl diff_mode show_diff;
  clean:
  rm -rf dist;
  