How can I force gnu make to not build recipe in parallel?

Question

How can I tell gnu make not to build some recipe in parallel. Let's say I have the following makefile :

sources = a.xxx b.xxx c.xxx
target  = program

all : $(target)

$(target) : $(patsubst %.xxx,%.o,$(sources))
    $(CXX) -o $@ $<

%.o : %.cpp
    $(CXX) -c -o $@ $<

%.cpp : %.xxx
    my-pre-processor -o $@ $<

However, the my-pre-processor command create temporary files with fixed name (I cannot change this). This is working fine if I just use make without the -j parameter. However, if the -j option is used, the build sometimes fails because two concurrent invocation of my-pre-processor overwrite their temporary files.

I'd like to know if there is a way to tell make that it must not build the try to parallelize the execution of the %.cpp : %.xxx recipes.

Answer 1

Solution 1

GNU Make contains the special built-in pseudo-target .NOTPARALLEL

Example:

.PHONY: all clean

.NOTPARALLEL:

anotherTarget: dependency1

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Solution 2

You can also use the -j <n>,--jobs[=<n>] flag on the command line where n is the number of recipies allowed to run in parallel.

Usage: make -j <n> or make --jobs=<n>

Example: make -j 1 or make --jobs=1

note: omitting <n> will allow an arbitrary number of recipes to be executed, only limited by your system's available resources

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Solution 3

Finally, you can assign the command line flag in solution 2 to the MAKEFLAGS variable from within your Makefile

Example: MAKEFLAGS := -j 1 or MAKEFLAGS := --jobs=1