How come Haskell got a segmentation fault when the vector is very large but under memory limit?

Question

I wanted to write a program that operates on a really large array, and does a lot of random access read/write operations. I figured vector is the most suitable way of doing it in Haskell, so I wrote a simple program to test its performance:

import Data.Int
import qualified Data.Vector.Unboxed.Mutable as UM

n = 1000000000

main = do
    a <- UM.new n
    UM.read a 42 :: IO Int32

However, when I ran it, it failed with segmentation fault:

$ ghc -O2 test.hs
$ ./test
Segmentation fault (core dumped)

This machine has more than enough memory for the array. Here is the output of free -h:

             total       used       free     shared    buffers     cached
Mem:          251G       150G       100G       672K       419M       141G
-/+ buffers/cache:       9.2G       242G
Swap:         255G       870M       255G

Was it because Haskell's vector package cannot handle very large arrays? Can I modify my code so that it can work on large arrays without too much performance compromise?

---

Edit: My GHC version is 7.10.2.20150906, and my vector version is 0.11.0.0. This is on a 64-bit linux machine, with

> maxBound :: Int
9223372036854775807

Answer 1

This is due to a bug in primitive that is apparently fixed in the recently-released primitive-0.6.1.0. I suggest you add a lower bound on primitive to your project accordingly.