Re: [Haskell-cafe] Re: bizarre memory usage with data.binary

3 Oct 2007

      servers never terminate, pretend that i have a server that reads a
list encoded with data.binary from a socket, and sums it up and
returns the current sum.  i would expect it to run in constant memory,
never terminate, and do useful work.

which is basically the problem that I am facing right now.  my program
seems to grow randomly in memory use when marshaling large data types
encoded using data.binary.

On 10/2/07, Dan Weston  wrote:
...
Maybe what you are observing is that the operational semantics of
undefined is undefined. The program can halt, run forever, use no
memory, use all the memory.
Although I doubt what GHC does with this code is a random process, I
don't think it's too meaningful to ask what are the space usage patterns
of a program returning bottom.
Anatoly Yakovenko wrote:
...
Program1:
module Main where
import Data.Binary
import Data.List(foldl')
main = do
  let sum' = foldl' (+) 0
  let list::[Int] = decode $ encode $ ([1..] :: [Int])
  print $ sum' list
  print "done"
vs
Program2:
module Main where
import Data.Binary
import Data.List(foldl')
main = do
  let sum' = foldl' (+) 0
  let list::[Int] = [1..]
  print $ sum' list
  print "done"
neither program is expected to terminate.  The point of these examples
is to demonstrate that Data.Binary encode and decode have some strange
memory allocation patters.
If you run Program1, it will run forever, but its memory usage on my
machine goes to 500M then back down to 17M then back up to 500M then
back down to 17M... repeatedly.  I don't think this has anything to do
with running out of space in a 32 bit integer.
Program2 on the other hand runs at constant memory at around 2M.
Anatoly
On 10/2/07, Anatoly Yakovenko  wrote:
...
i am getting some weird memory usage out of this program:
module Main where
import Data.Binary
import Data.List(foldl')
main = do
   let sum' = foldl' (+) 0
   let list::[Int] = decode $ encode $ ([1..] :: [Int])
   print $ sum' list
   print "done"
it goes up to 500M and down to 17M on windows.  Its build with ghc
6.6.1 with the latest data.binary
Any ideas what could be causing the memory usage to jump around so much?
Thanks,
Anatoly
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