Build races when using make -j8 ?

[Ben Lippmeier]

Hi All,
When I build with "make -j8" on my dept T2 (mavericks) I'm getting what 
looks like build races. Has anyone seen this problem before?

Not being a make or unix file system expert, my only guess is that the 
interface file is being written to the FS in chunks, and that make is 
trying to compile modules that depend on it before the file is all 
there. However, that seems so obvious that someone would have noticed 
and fixed it by now.

The machine reports:
benl at mavericks:~> uname -a
SunOS mavericks 5.10 Generic_127127-11 sun4v sparc 
SUNW,SPARC-Enterprise-T5120

I get the problem after:
$ make distclean
$ sh boot
$ ./configure

$ make -j8
... runs for a while then gives:
/data0/home/benl/software/ghc-6.8.3/bin/ghc -#include cutils.h -DSTAGE=1 
... -XRelaxedPolyRec -idist-stage1/build  -H64m -O0 -fvia-c -Rghc-timing 
-O0  -c simplCore/CSE.lhs -o dist-stage1/build/CSE.o  -ohi 
dist-stage1/build/CSE.hi

coreSyn/CoreLint.lhs:40:0:
    Bad interface file: dist-stage1/build/ListSetOps.hi
        magic number mismatch: old/corrupt interface file?


-- so I start make again ------------------------------
$ make -j8
... runs for a while then gives:

/data0/home/benl/software/ghc-6.8.3/bin/ghc -#include cutils.h -DSTAGE=1 
... -XRelaxedPolyRec -idist-stage1/build  -H64m -O0 -fvia-c -Rghc-timing 
-O0  -c coreSyn/CoreTidy.lhs -o dist-stage1/build/CoreTidy.o  -ohi 
dist-stage1/build/CoreTidy.hi

coreSyn/CoreTidy.lhs:27:0:
    Bad interface file: dist-stage1/build/Maybes.hi
        magic number mismatch: old/corrupt interface file?


-- one more time! --------------------------------------
$ make -j8
... runs for a while then gives:

/data0/home/benl/software/ghc-6.8.3/bin/ghc -#include cutils.h -DSTAGE=1 
... -XRelaxedPolyRec -idist-stage1/build  -H64m -O0 -fvia-c -Rghc-timing 
-O0  -c codeGen/CgMonad.lhs -o dist-stage1/build/CgMonad.o  -ohi 
dist-stage1/build/CgMonad.hi
<<ghc: 53024912 bytes, 13 GCs, 2272460/6893568 avg/max bytes residency 
(5 samples), 66M in use, 0.01 INIT (0.00 elapsed), 0.69 MUT (4.44 
elapsed), 0.41 GC (2.61 elapsed) :ghc>>

codeGen/CgMonad.lhs:62:0:
    Bad interface file: dist-stage1/build/CgBindery.hi-boot
        magic number mismatch: old/corrupt interface file?


-- sigh, so I give up and just use a single thread ------
$ make
... build completes with no further problems.