[GHC] #15449: Nondeterministic Failure on aarch64 with -jn, n > 1

[GHC]

#15449: Nondeterministic Failure on aarch64 with -jn, n > 1
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        Reporter:  tmobile           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.4.3
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:  aarch64
 Type of failure:  Compile-time      |            Test Case:
  crash or panic                     |
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by tmobile):

 Attaching GDB to a hung GHC, looks like it's just stuck on a futex:

 {{{
 #0  0x0000007fa5459100 in futex_wait_cancelable (private=<optimized out>,
 expected=0, futex_word=0x60939c) at ../sysdeps/unix/sysv/linux/futex-
 internal.h:88
 #1  __pthread_cond_wait_common (abstime=0x0, mutex=0x6093a0,
 cond=0x609370) at pthread_cond_wait.c:502
 #2  __pthread_cond_wait (cond=0x609370, mutex=0x6093a0) at
 pthread_cond_wait.c:655
 #3  0x0000007fa56815e8 in waitCondition () from /nix/store
 /dcwj7hvxgzqj7kbmfklqh4kg635ra7pk-ghc-8.4.3-binary-aarch64/lib/aarch64
 -unknown-linux-gnu-ghc-8.4.3/bin/../rts/libHSrts_thr-ghc8.4.3.so
 Backtrace stopped: previous frame identical to this frame (corrupt stack?)
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15449#comment:1>
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