Making the FSharp interpreter (fsi) run in 64bit!

I love F#!  It’s all the power of functional programming with the training wheels of c# when you need it. All the prototype/REPL power of powershell and python, with the built in test cases I like to call static typing. All the power of static typing, with out the hassle of specifying types every where thanks to implicit typing.

But, there is one annoying problem, I crunch very large data sets and fsi.exe runs as a 32 bit application. This means when I load my data sets and iterate through them FSI takes up 1.6 GB of RAM (maximum for a 32bit app), and spends 100% of its time in GC.

An aside for you who are thinking: 1.6GB is enough RAM!? – Igor must be a really crappy programmer!!! 1.6GB could be plenty, but why should I spend time adding complexity to my code when I have a superb memory manager, a 64 bit address space and a 3 year old dev machine that has 16GB of RAM, and 8 processors?  Today, I get no value from optimizing my data set for memory utilization -- I’m better off making my data cruncher a 64 bit application.

Back to work.  First, lets open up the Visual Studio command prompt (it has the tools we need in its path) and find fsi.exe.

C:\Program Files (x86)\Microsoft F#\v4.0>dir fsi.*
 Volume in drive C has no label.
 Volume Serial Number is 8EDE-D64E

 Directory of C:\Program Files (x86)\Microsoft F#\v4.0

03/19/2010  02:02 PM           230,216 Fsi.exe
09/30/2009  08:08 PM               158 Fsi.exe.config
               2 File(s)        230,374 bytes

Lets make sure it's 32 bit - we do that with a tool called corflags.

C:\Program Files (x86)\Microsoft F#\v4.0>corflags fsi.exe
Microsoft (R) .NET Framework CorFlags Conversion Tool.  Version  4.0.30319.1
Copyright (c) Microsoft Corporation.  All rights reserved.

Version   : v4.0.30319
CLR Header: 2.5
PE        : PE32
CorFlags  : 11
ILONLY    : 1
32BIT     : 1
Signed    : 1

Next we use corflags to make fsi 64bit. This will unsign the fsi.exe but this hasn't affected anything for me yet.

 

C:\Program Files (x86)\Microsoft F#\v4.0>corflags /32bit- /force fsi.exe
Microsoft (R) .NET Framework CorFlags Conversion Tool.  Version  4.0.30319.1
Copyright (c) Microsoft Corporation.  All rights reserved.

corflags : warning CF011 : The specified file is strong name signed.  Using /For
ce will invalidate the signature of this image and will require the assembly to
be resigned.

Lets double check it worked:

 
C:\Program Files (x86)\Microsoft F#\v4.0>corflags fsi.exe
Microsoft (R) .NET Framework CorFlags Conversion Tool.  Version  4.0.30319.1
Copyright (c) Microsoft Corporation.  All rights reserved.

Version   : v4.0.30319
CLR Header: 2.5
PE        : PE32
CorFlags  : 9
ILONLY    : 1
32BIT     : 0
Signed    : 1

Finally fire up F#, and it's now in 64 bit - yippee!

Posted in: f#