# Custom serialization problem 2 (marshal\_dump, marshal\_load)

**URL:** <https://www.ruby-forum.com/t/custom-serialization-problem-2-marshal-dump-marshal-load/196687>\
**Category:** Ruby\
**Created:** [May 21, 2008, 7:54pm UTC](https://www.ruby-forum.com/t/custom-serialization-problem-2-marshal-dump-marshal-load/196687 "2008-05-21T19:54:12Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![sayoyo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ba8739/32.png) [@sayoyo](https://www.ruby-forum.com/u/sayoyo)\
**Post date:** [May 21, 2008, 7:54pm UTC](https://www.ruby-forum.com/t/custom-serialization-problem-2-marshal-dump-marshal-load/196687/1 "2008-05-21T19:54:12Z")

</div>

Hi,

I have a problem with the marshal\_dump and marshal\_load…  
I built two classes XXX, YYY and implemented both methods like this:

class YYY  
@data = “string”  
@version = 1

def marshal\_dump()  
return [@version,@data]  
end

def marshal\_load(var)  
@version = var[0]  
case @version  
when 1  
@data = var[1]  
else  
#do something else  
end  
end  
end

class XXX  
@data = Array of YYY  
@version = 1

def marshal\_dump()  
return [@version,@data]  
end

def marshal\_load(var)  
@version = var[0]  
case @version  
when 1  
@data = var[1]  
else  
#do something else  
end  
end  
end

The serialization works correctly when the number of objects YYY is  
small, but when it got more than 5000, the serialization doesn’t work.  
(the serializaed file has more and less 1 meg)

When I try to not to use marshal\_dump and marshal\_load. the  
serialization works again???

Can someone tell me, where is the difference between customized  
serialization and no-customized one???

Thanks you very much

Sayoyo

---

<div class="post-metadata">

**Author:** ![sayoyo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ba8739/32.png) [@sayoyo](https://www.ruby-forum.com/u/sayoyo)\
**Post date:** [May 21, 2008, 10:24pm UTC](https://www.ruby-forum.com/t/custom-serialization-problem-2-marshal-dump-marshal-load/196687/2 "2008-05-21T22:24:43Z")

</div>

Joel VanderWerf wrote:

> ```
> @data = (0..1000).map { YYY.new }
> 
> ```

I tried it for 1\_000\_000 with no problem, and that generated a 1.4Mb  
file.

Ruby 1.8.6-p114, linux.

---

<div class="post-metadata">

**Author:** ![sayoyo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ba8739/32.png) [@sayoyo](https://www.ruby-forum.com/u/sayoyo)\
**Post date:** [May 21, 2008, 10:16pm UTC](https://www.ruby-forum.com/t/custom-serialization-problem-2-marshal-dump-marshal-load/196687/3 "2008-05-21T22:16:27Z")

</div>

sayoyo Sayoyo wrote:

> ```
> return [@version,@data]
> 
> ```
> 
> end  
> def marshal\_load(var)  
> The serialization works correctly when the number of objects YYY is  
> Thanks you very much
> 
> Sayoyo

What version of ruby? What platform?

Same problem when you serialize to memory instead of file?

What exactly is the observed problem? Crash, exception, data error?

The following version of your code seems to work:

class YYY  
attr\_reader :data, :version

def initialize  
@data = “string”  
@version = 1  
end

def marshal\_dump()  
return [@version,@data]  
end

def marshal\_load(var)  
@version = var[0]  
case @version  
when 1  
@data = var[1]  
else  
#do something else  
end  
end  
end

class XXX  
attr\_reader :data, :version

def initialize  
@data = (0…1000).map { YYY.new }  
@version = 1  
end

def marshal\_dump()  
return [@version,@data]  
end

def marshal\_load(var)  
@version = var[0]  
case @version  
when 1  
@data = var[1]  
else  
#do something else  
end  
end  
end

xxx = XXX.new

x2 = Marshal.load(Marshal.dump(xxx))

p x2.data[777]

File.open(’/tmp/foo’, “wb”) do |f|  
Marshal.dump(xxx, f)  
end

x3 = File.open(’/tmp/foo’, “rb”) do |f|  
Marshal.load(f)  
end

p x3.data[888]

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<div class="post-metadata">

**Author:** ![sayoyo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ba8739/32.png) [@sayoyo](https://www.ruby-forum.com/u/sayoyo)\
**Post date:** [May 22, 2008, 3:26am UTC](https://www.ruby-forum.com/t/custom-serialization-problem-2-marshal-dump-marshal-load/196687/4 "2008-05-22T03:26:33Z")

</div>

sayoyo Sayoyo wrote:

> The example I posted here is an simplification of my data, actually I
> 
> and each of them have more and less 10 attributes… When I have 5000 of  
> B, the serialized file has almost 1 meg. And I also realized each time I  
> serialized the same data, the file got a different size each time…
> 
> How can I verify the serailization?

I would try to come up with a minimal characterization of the  
problem–minimize the classes, attrs, objects so that if you take away  
anything else the problem goes away. That should help point to the  
problem.

Also, you could try running this on other systems and ruby versions…

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<div class="post-metadata">

**Author:** ![sayoyo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ba8739/32.png) [@sayoyo](https://www.ruby-forum.com/u/sayoyo)\
**Post date:** [May 21, 2008, 10:56pm UTC](https://www.ruby-forum.com/t/custom-serialization-problem-2-marshal-dump-marshal-load/196687/5 "2008-05-21T22:56:15Z")

</div>

Hi,

I’m using ruby 1.8.6 (2007-09-24 patchlevel 111) [x86\_64-linux] and  
Rails 1.2.5

The problem I have, is the class XXX should have an array of YYY as  
data, but it turn out I got only NIL when I deserialized, then I got an  
exception for unable to use [] for a NIL. It happens only when I have a  
lot of data.

The example I posted here is an simplification of my data, actually I  
have 5 classes, the structure:  
A–  
|-Array of B  
|- C

B–  
|-Array of D

C–  
|-Array of E

and each of them have more and less 10 attributes… When I have 5000 of  
B, the serialized file has almost 1 meg. And I also realized each time I  
serialized the same data, the file got a different size each time…

How can I verify the serailization?