[Haskell-cafe] Unnecessarily strict implementations

[Jan Christiansen]

On 03.09.2010, at 14:38, Daniel Fischer wrote:

> I can't reproduce that. For me, it leaks also with profiling.

Have you used optimizations? It disappears if I compile the program  
with -O2.

Without profiling I get the following. Here the maximum residency is  
nearly 45MB.

$ ghc --make Temp.hs -fforce-recomp
[1 of 1] Compiling Main             ( Temp.hs, Temp.o )
Linking Temp ...
$ ./Temp +RTS -sstderr
./Temp +RTS -sstderr
5458199
      647,520,792 bytes allocated in the heap
      256,581,176 bytes copied during GC
       44,934,408 bytes maximum residency (11 sample(s))
        1,363,496 bytes maximum slop
              103 MB total memory in use (1 MB lost due to  
fragmentation)

   Generation 0:  1223 collections,     0 parallel,  0.83s,  0.85s  
elapsed
   Generation 1:    11 collections,     0 parallel,  0.49s,  0.62s  
elapsed

   INIT  time    0.00s  (  0.00s elapsed)
   MUT   time    0.63s  (  0.67s elapsed)
   GC    time    1.32s  (  1.46s elapsed)
   EXIT  time    0.00s  (  0.00s elapsed)
   Total time    1.96s  (  2.13s elapsed)

   %GC time      67.6%  (68.5% elapsed)

   Alloc rate    1,022,883,082 bytes per MUT second

   Productivity  32.3% of total user, 29.6% of total elapsed


With profiling it looks as follows. Here the maximum residency is less  
than 15KB.

$ ghc --make Temp.hs -prof -auto-all -fforce-recomp
[1 of 1] Compiling Main             ( Temp.hs, Temp.o )
Linking Temp ...
$ ./Temp +RTS -sstderr
./Temp +RTS -sstderr
5458199
    1,051,844,836 bytes allocated in the heap
      110,134,944 bytes copied during GC
           14,216 bytes maximum residency (96 sample(s))
           37,068 bytes maximum slop
                2 MB total memory in use (0 MB lost due to  
fragmentation)

   Generation 0:  1908 collections,     0 parallel,  0.57s,  0.59s  
elapsed
   Generation 1:    96 collections,     0 parallel,  0.02s,  0.02s  
elapsed

   INIT  time    0.00s  (  0.00s elapsed)
   MUT   time    1.46s  (  1.51s elapsed)
   GC    time    0.60s  (  0.61s elapsed)
   RP    time    0.00s  (  0.00s elapsed)
   PROF  time    0.00s  (  0.00s elapsed)
   EXIT  time    0.00s  (  0.00s elapsed)
   Total time    2.05s  (  2.12s elapsed)

   %GC time      29.0%  (28.7% elapsed)

   Alloc rate    721,170,248 bytes per MUT second

   Productivity  71.0% of total user, 68.9% of total elapsed