When excute “make px4_sitl jmavsim” it stopped at PX4 ECL

When excute “make px4_sitl jmavsim” it stopped at PX4 ECL as follows.
What’s the problem?
Would anyone please help me fix it?

make px4_sitl jmavsim

– PX4 config file: /home/shelley/src/Firmware/boards/px4/sitl/default.cmake
– PX4 config: px4_sitl_default
– PX4 platform: posix
– PX4 lockstep: enabled
– PX4 version: v1.9.0-326-gfecb32f88d
– cmake build type: RelWithDebInfo
– The CXX compiler identification is GNU 7.4.0
– The C compiler identification is GNU 7.4.0
– The ASM compiler identification is GNU
– Found assembler: /usr/bin/cc
– Check for working CXX compiler: /usr/bin/c++
– Check for working CXX compiler: /usr/bin/c++ – works
– Detecting CXX compiler ABI info
– Detecting CXX compiler ABI info - done
– Detecting CXX compile features
– Detecting CXX compile features - done
– Check for working C compiler: /usr/bin/cc
– Check for working C compiler: /usr/bin/cc – works
– Detecting C compiler ABI info
– Detecting C compiler ABI info - done
– Detecting C compile features
– Detecting C compile features - done
– Found PythonInterp: /usr/bin/python (found version “2.7.15”)
– Found PY_jinja2: /usr/lib/python2.7/dist-packages/jinja2
– PX4 ECL: Very lightweight Estimation & Control Library v1.9.0-rc1-16-ga036cf8

Oh, only need to wait. It’s slow.
Is it normal that the building process is so slowly?