New space leak?

[Simon Peyton-Jones]

It would be very helpful if someone felt able to do some space profiles of GHC itself, using 7.4, 7.6 and the new HEAD, to see whether residency (the amount of head in use at any moment) has increased. And if so, why.

Any takers?

Simon

From: ghc-devs [mailto:ghc-devs-bounces at haskell.org] On Behalf Of Simon Marlow
Sent: 01 October 2013 10:01
To: ghc-devs at haskell.org
Subject: New space leak?

My validate has a few perf failures (below).  Now I know that sampling heap size is inaccurate, but the evidence here is pretty strong. Also validate fell over completely in my 2GB VM when Haddock ran out of memory, I had to give it more memory to complete.  Something has got worse recently - this wasn't happening a couple of weeks ago.
Does anyone have any idea what might have caused this?  Going back in time is difficult.  Are these failures happening for other people?
Let me suggest something that might help with these perf tests: running the program with +RTS -h -i0.01 will give a more accurate indication of peak residency, by running major GCs much more often.  Also you get a heap profile.

Cheers,
Simon

=====> haddock.base(normal) 2474 of 3806 [0, 1, 0]
max_bytes_used value is too high:
    Expected    max_bytes_used:  96022312 +/-10%
    Lower bound max_bytes_used:  86420080
    Upper bound max_bytes_used: 105624544
    Actual      max_bytes_used: 113537216
peak_megabytes_allocated value is too high:
    Expected    peak_megabytes_allocated: 274 +/-10%
    Lower bound peak_megabytes_allocated: 246
    Upper bound peak_megabytes_allocated: 302
    Actual      peak_megabytes_allocated: 323
*** unexpected failure for haddock.base(normal)
=====> haddock.Cabal(normal) 2475 of 3806 [0, 2, 0]
=====> haddock.compiler(normal) 2476 of 3806 [0, 2, 0]
peak_megabytes_allocated value is too high:
    Expected    peak_megabytes_allocated: 1250 +/-10%
    Lower bound peak_megabytes_allocated: 1125
    Upper bound peak_megabytes_allocated: 1375
    Actual      peak_megabytes_allocated: 1397
bytes allocated value is too high:
    Expected    bytes allocated: 25990254632 +/-10%
    Lower bound bytes allocated: 23391229168
    Upper bound bytes allocated: 28589280096
    Actual      bytes allocated: 28680445952
*** unexpected failure for haddock.compiler(normal)
=====> T3064(normal) 2480 of 3806 [0, 3, 0]
cd ./perf/compiler && '/home/smarlow/ghc/bindisttest/install   dir/bin/ghc' -fforce-recomp -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c T3064.hs   +RTS -V0 -tT3064.comp.stats --machine-readable -RTS  >T3064.comp.stderr 2>&1
max_bytes_used value is too high:
    Expected    max_bytes_used: 12000480 +/-20%
    Lower bound max_bytes_used:  9600384
    Upper bound max_bytes_used: 14400576
    Actual      max_bytes_used: 15258696
peak_megabytes_allocated value is too high:
    Expected    peak_megabytes_allocated: 30 +/-20%
    Lower bound peak_megabytes_allocated: 24
    Upper bound peak_megabytes_allocated: 36
    Actual      peak_megabytes_allocated: 37
*** unexpected failure for T3064(normal)
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