From: Jamey Cribbs <jcribbs@...>
Date: 2006-12-09T04:05:20+09:00
Subject: Re: Marshal::dump error on PowerBook G4

Emmett Shear wrote:
> I've written code for a Splay tree in Ruby, and I'm trying to
> serialize it using Marshal::dump.
>
> If I create a tree with 1,000 or 10,000 nodes, Marshal::dump works
> perfectly. When I get up to 100,000 nodes, Marshal::dump causes the
> irb process to die with the error "Illegal Instruction".
>
> Is this a known problem? I tried searching for "Marshal::dump" and
> "Illegal Instruction" it but I didn't turn up anything. I'm on a
> PowerBook G4, running Ruby version 1.8.5 and IRb version 0.9.5. I've
> attached the code for the Splay tree; to reproduce, open irb and run:
>
> require 'splay'
> t = SplayTree.new
> 100000.times {|i| t[i] = i}
> Marshal::dump t

I remember running into something similar when I started working on 
Mongoose, which is a ruby rdbms that uses SkipLists for it's indexing.

If I tried to serialize the entire SkipList and it had too many keys, I 
would get an error.  I ended adding a method that converts the SkipList 
to a hash, then feeds the hash to Marshal.dump, and it worked.  I also 
have another method that loads the Marshalled hash and turns it back 
into a SkipList.

Another thing you could do would be to serialize each SplayNode, instead 
of the whole tree.

HTH,

Jamey Cribbs

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