[GHC] #8817: segmentation fault in 7.8 RC1

[GHC]

#8817: segmentation fault in 7.8 RC1
-------------------------------------+----------------------------------
        Reporter:  hamishmack        |            Owner:  simonmar
            Type:  bug               |           Status:  new
        Priority:  high              |        Milestone:  7.8.1
       Component:  Runtime System    |          Version:  7.8.1-rc1
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  x86_64 (amd64)
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
-------------------------------------+----------------------------------
Changes (by hvr):

 * cc: simonmar (added)
 * owner:   => simonmar
 * component:  Compiler => Runtime System


Comment:

 I suspect this is actually GC/RTS related; when using `-A4096`, the output
 of `+RTS -S` looks as below (I had to `CTRL-C` as it won't stop
 otherwise):

 {{{
     Alloc    Copied     Live    GC    GC     TOT     TOT  Page Flts
     bytes     bytes     bytes  user  elap    user    elap
      1256      1232      1224  0.00  0.00    0.00    0.00    0    0  (Gen:
 0)
         0      1208      1224  0.00  0.00    0.00    0.00    0    0  (Gen:
 0)
         0         0      1224  0.00  0.00    0.00    0.00    0    0  (Gen:
 0)
         0         0      1224  0.00  0.00    0.00    0.00    0    0  (Gen:
 0)
         0         0      1224  0.00  0.00    0.00    0.00    0    0  (Gen:
 0)
         0         0      1224  0.00  0.00    0.00    0.00    0    0  (Gen:
 0)
 ...
         0         0      1224  0.00  0.00    0.98    0.98    0    0  (Gen:
 0)
         0         0      1224  0.00  0.00    0.98    0.98    0    0  (Gen:
 0)
         0         0      1224  0.00  0.00    0.98    0.98    0    0  (Gen:
 0)
        72        72      1296  0.00  0.00    0.98    0.98    0    0  (Gen:
 0)
 cpphs: interrupted
      1024                      0.00  0.00

            2,352 bytes allocated in the heap
            2,512 bytes copied during GC
            6,968 bytes maximum slop
                1 MB total memory in use (0 MB lost due to fragmentation)

                                     Tot time (elapsed)  Avg pause  Max
 pause
   Gen  0     215256 colls,     0 par    0.29s    0.29s     0.0000s
 0.0000s
   Gen  1         0 colls,     0 par    0.00s    0.00s     0.0000s
 0.0000s

   INIT    time    0.00s  (  0.00s elapsed)
   MUT     time    0.69s  (  0.70s elapsed)
   GC      time    0.29s  (  0.29s elapsed)
   EXIT    time    0.00s  (  0.00s elapsed)
   Total   time    0.98s  (  0.98s elapsed)

   %GC     time      29.3%  (29.1% elapsed)

   Alloc rate    3,390 bytes per MUT second

   Productivity  70.7% of total user, 70.8% of total elapsed
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8817#comment:3>
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