looking for assistance with "parallel" makefile, willing to pay

[Robert P. J. Day]

  (not sure if this is appropriate, but i have a makefile just dropped
in my lap that has some issues, and if someone can clean it up, i'll
do better than virtual beer, i'll do real compensation. i'd be happy
to interac the problem solver $100 (CAD), so here we go.)

  here is a package that is being built for x86-64 using wind river
linux 9:

  https://github.com/juniper/jp4agent

as you can see, there has been some attempt to add parallelization to
this makefile, which appears to be exactly what the problem is.

  if you look at the top-level Makefile, a whole pile of things
depends on the same thing -- src/pi/protos:

  src/pi/protos: AFI
  src/pi/src: src/pi/protos
  src/jp4agent/src: src/pi/protos src/pi/src
  src/utils/src: src/pi/protos
  src/afi/src: src/pi/protos
  test/controller/src: src/pi/protos
  test/gtest/src: src/pi/protos
  src/targets/null/null/src: src/pi/protos

and it's just that Makefile under src/pi/protos that, intermittently,
generates the following build error (i don't think there's anything
here i need to redact for security):

... much snipped ...
19:29:13 | cp: cannot create regular file
'/build/jenkins/workspace/WRL9-build/daily/tmp/work/core2-64-poky-linux/jp4agent/git-r0/image/usr/include/jp4agent/src/pi/./protos/status.pb.h':
File exists
19:29:13 | cp: cannot create regular file
'/build/jenkins/workspace/WRL9-build/daily/tmp/work/core2-64-poky-linux/jp4agent/git-r0/image/usr/include/jp4agent/src/pi/protos/./p4info.grpc.pb.h':
File exists
19:29:13 | make[1]: *** [Makefile:166: install] Error 1
19:29:13 | make[1]: Leaving directory
'/build/jenkins/workspace/WRL9-build/daily/tmp/work/core2-64-poky-linux/jp4agent/git-r0/git/src/pi/protos'
19:29:13 | make: *** [Makefile:58: install-src/pi/protos] Error 2
19:29:13 | make: *** Waiting for unfinished jobs....
19:29:13 | make[1]: Leaving directory
'/build/jenkins/workspace/WRL9-build/daily/tmp/work/core2-64-poky-linux/jp4agent/git-r0/git/src/afi/src'
19:29:13 | make[1]: *** [Makefile:104: install] Error 1
19:29:13 | make[1]: Leaving directory
'/build/jenkins/workspace/WRL9-build/daily/tmp/work/core2-64-poky-linux/jp4agent/git-r0/git/src/pi/src'
19:29:13 | make: *** [Makefile:58: install-src/pi/src] Error 2

  those "File exists" errors appear to be a race condition as
described here:

https://unix.stackexchange.com/questions/116280/cannot-create-regular-file-filename-file-exists

and if you head down to src/pi/protos/Makefile, sure enough, at line
166:

.PHONY: install
install: $(TARGET_LIB)
        install -d $(DESTDIR)$(prefix)/lib64/
        install -m 644 $(wildcard *.so.*) $(DESTDIR)$(prefix)/lib64/
        rm -f $(DESTDIR)$(prefix)/lib64/${basename $(TARGET_LIB)}
        ln -s ${notdir $(TARGET_LIB)} $(DESTDIR)$(prefix)/lib64/${basename 
$(TARGET_LIB)}
        install -d $(DESTDIR)$(prefix)/include/jp4agent
        install -d $(DESTDIR)$(prefix)/include/jp4agent/src
        install -d $(DESTDIR)$(prefix)/include/jp4agent/src/pi
        install -d $(DESTDIR)$(prefix)/include/jp4agent/src/pi/protos
166     cp --parents `find -name \*.h` 
$(DESTDIR)$(prefix)/include/jp4agent/src/pi/protos

  as you can see, that cp command tries to copy a pile of header files
elsewhere, and that certainly seems to be the cause of this (alleged)
race condition.

  i've only started looking at this today, so it's going to take a
while to wrap my head around this, but it's hard to see how that error
can be other than a race condition based on the parallelization that's
been added to this code base.

  if someone wants to isolate the problem and fix it, i'd be a happy
camper as i have lots of other stuff to work on.

  thoughts?

rday

p.s. finding a way to reproduce the build error would be just ducky,
too.