incorrect handling of error codes with -j flag

[Colin Girling]

We have identified a situation where make will randomly return 2 or 0 for the same recipe.

 

Our build system compiles unit tests, runs the unit test executable and then performs some basic clean-up after the test is run.

We have something like this:

 

$(derived_dir)/app /unit_tests/%_tests.pass: \

                                app/%.cpp \

                                app/unit_tests/%_tests.cpp \

                                $(PTLIBDOBJS)

                $(AT)$(call PTCOMPILECPP,$(TEMP)/app -$(subst /,-,$*)_tests$(PTOBJEXT),app_orion_picasso_resources/unit_tests/$*_tests.cpp)

                $(AT)$(call PTRUN,$(TEMP)/app-$(subst /,-,$*)$(PTEXT)) $(programmer_test_flags)

                $(AT)$(PYTHON) $(MAKEROOT)/rm.py $(TEMP)/app-$(subst /,-,$*)$(PTEXT) $(TEMP)/app-$(subst /,-,$*)_tests$(PTOBJEXT) $(TEMP)/app-$(subst /,-,$*)$(PTOBJEXT)

                $(AT)$(PYTHON) $(MAKEROOT)/rm.py -f $(TEMP)/app-$(subst /,-,$*).pdb

                $(AT)$(PYTHON) $(MAKEROOT)/touch.py $@

 

We execute rm.py and touch.py instead of Linux commands to handle porting issues for Windows and Linux, but the basics are the unit test will be deleted when the test passes, or be left in the file system if the test fails.

The unit test executable will return error code 2 when it fails, then make returns 0 or 2 when a unit test fails.

 

We tested this with -j8 and can see the return code is randomly returned as 0 or 2 each time we compile and run the test, but with -j1 make will always return 0.

We fixed the problem by placing – in front of the rm.py and touch.py commands, but it seems there is some sort of multi-process issue here, and I would still expect 0 to always be returned with this problem in the makefile.

We would also expect these lines to be treated as sequential in a single process, but is that actually happening?

 

We are also using the gnu make build on Windows, and the behaviour is consistently behaving the same for -j1 and -j8, so it appears to only be a problem for Linux.

 

 

Regards,

Colin Girling

 

IMPORTANT NOTICE: This e-mail message is intended to be received only by persons entitled to receive the confidential information it may contain. E-mail messages to clients of Cabot Commuications Ltd may contain information that is confidential and legally privileged. Please do not read, copy, forward, or store this message unless you are an intended recipient of it. If you have received this message in error, please forward it to the sender and delete it completely from your computer system. Cabot Communications Limited is a company registered in England and Wales Registered Office: Unit A Link House, Britton Gardens, Kingswood, Bristol BS15 1TF. Company Registered in England Number 02817269.