make -j2 test

Makefile

CC=gcc
l.a : l.a(a.o)
    ranlib l.a
    echo done

l.a(a.o) : a.c

clean::
    rm -f l.a a.o

test.sh

touch a.c
while { make clean; make -j2; } &> test.out; grep -q ranlib test.out; do echo -n .; done; echo
while { make clean; make -j2; } &> test.out.ranlib; ! grep -q ranlib test.out.ranlib; do echo -n .; done; echo

Output

$ sh test.sh
..
.....................
::::::::::::::
test.out
::::::::::::::
rm -f l.a a.o
gcc    -c -o a.o a.c
ar rv l.a a.o
ar: creating l.a
a - a.o
::::::::::::::
test.out.ranlib
::::::::::::::
rm -f l.a a.o
gcc    -c -o a.o a.c
ar rv l.a a.o
ar: creating l.a
a - a.o
ranlib l.a
echo done
done