# Marshal::dump error on PowerBook G4

**URL:** <https://www.ruby-forum.com/t/marshal-dump-error-on-powerbook-g4/78804>\
**Category:** Ruby\
**Created:** [December 8, 2006, 7:23pm UTC](https://www.ruby-forum.com/t/marshal-dump-error-on-powerbook-g4/78804 "2006-12-08T19:23:44Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![emmett](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/f0a364/32.png) [@emmett](https://www.ruby-forum.com/u/emmett)\
**Post date:** [December 8, 2006, 7:23pm UTC](https://www.ruby-forum.com/t/marshal-dump-error-on-powerbook-g4/78804/1 "2006-12-08T19:23:44Z")

</div>

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

Thanks for any help,  
Emmett

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**Author:** ![emmett](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/f0a364/32.png) [@emmett](https://www.ruby-forum.com/u/emmett)\
**Post date:** [December 8, 2006, 9:12pm UTC](https://www.ruby-forum.com/t/marshal-dump-error-on-powerbook-g4/78804/2 "2006-12-08T21:12:03Z")

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On 12/8/06, Jamey C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> > PowerBook G4, running Ruby version 1.8.5 and IRb version 0.9.5. I’ve  
> > If I tried to serialize the entire SkipList and it had too many keys, I  
> > Jamey C.
> 
> Confidentiality Notice: This email message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and/or privileged information. If you are not the intended recipient(s), you are hereby notified that any dissemination, unauthorized review, use, disclosure or distribution of this email and any materials contained in any attachments is prohibited. If you receive this message in error, or are not the intended recipient(s), please immediately notify the sender by email and destroy all copies of the original message, including attachments.

Thanks, I tried the to\_hash workaround and it worked great. It also  
reduced the serialized size by a large margin. I’m still slightly  
disturbed by Marshal::dump dying so badly, but that definitely solved  
the problem.

Emmett

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**Author:** ![emmett](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/f0a364/32.png) [@emmett](https://www.ruby-forum.com/u/emmett)\
**Post date:** [December 8, 2006, 8:05pm UTC](https://www.ruby-forum.com/t/marshal-dump-error-on-powerbook-g4/78804/3 "2006-12-08T20:05:49Z")

</div>

Emmett S. wrote:

> 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 C.

Confidentiality Notice: This email message, including any attachments,  
is for the sole use of the intended recipient(s) and may contain  
confidential and/or privileged information. If you are not the intended  
recipient(s), you are hereby notified that any dissemination,  
unauthorized review, use, disclosure or distribution of this email and  
any materials contained in any attachments is prohibited. If you receive  
this message in error, or are not the intended recipient(s), please  
immediately notify the sender by email and destroy all copies of the  
original message, including attachments.

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**Author:** ![emmett](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/f0a364/32.png) [@emmett](https://www.ruby-forum.com/u/emmett)\
**Post date:** [December 9, 2006, 5:30am UTC](https://www.ruby-forum.com/t/marshal-dump-error-on-powerbook-g4/78804/4 "2006-12-09T05:30:52Z")

</div>

Hi,

In message “Re: Marshal::dump error on PowerBook G4”  
on Sat, 9 Dec 2006 03:21:51 +0900, “Emmett S.”  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) writes:

|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”.

Marshal uses recursion to traverse objects and OSX has far smaller  
stack rlimits than other platforms. As a result of combination of  
above, marshaling an object with long reference chain may cause  
unexpected process termination. It is pretty diffucult to fix.

```
						matz.

```

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**Author:** ![emmett](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/f0a364/32.png) [@emmett](https://www.ruby-forum.com/u/emmett)\
**Post date:** [December 9, 2006, 1:54am UTC](https://www.ruby-forum.com/t/marshal-dump-error-on-powerbook-g4/78804/5 "2006-12-09T01:54:38Z")

</div>

On Dec 8, 2006, at 10:21 , Emmett S. wrote:

> 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 think you ran out of something because your C stack is huge.

(gdb) run splay.rb  
Starting program: /usr/local/bin/ruby splay.rb  
Reading symbols for shared libraries … done

Program received signal EXC\_BAD\_ACCESS, Could not access memory.  
Reason: KERN\_INVALID\_ADDRESS at address: 0xbf7fffc0  
0x00064bbc in str\_independent (str=1854980) at string.c:474  
474 {  
(gdb) bt  
#0 0x00064bbc in str\_independent (str=1854980) at string.c:474  
#1 0x00064d34 in rb\_str\_modify (str=1854980) at string.c:505  
#2 0x0006540c in rb\_str\_buf\_cat (str=1854980, ptr=0xbf800178 “\b??  
T”, len=1) at string.c:706  
#3 0x0008bf28 in w\_nbyte (s=0x64d34 “/?”, n=1, arg=0xbfffe854) at  
marshal.c:128  
#4 0x0008bfb4 in w\_byte (c=8 ‘\b’, arg=0x1) at marshal.c:141  
#5 0x0008c088 in w\_long (x=1, arg=0xbfffe854) at marshal.c:183  
#6 0x0008c5b8 in w\_symbol (id=10154, arg=0xbfffe854) at marshal.c:336  
#7 0x0008c9b8 in w\_obj\_each (id=1854980, value=171689,  
arg=0xbf800428) at marshal.c:428  
#8 0x00056394 in foreach\_safe\_i (key=412980, value=3212837240,  
arg=0x1) at hash.c:131  
#9 0x0007756c in st\_foreach (table=0x2b9c200, func=0x56360  
\<foreach\_safe\_i\>, arg=3212837752) at st.c:487  
#10 0x000563e4 in st\_foreach\_safe (table=0x1c4e04, func=0xbf800178,  
a=1) at hash.c:149  
#11 0x0008ca24 in w\_ivar (tbl=0x2b9c200, arg=0xbf800428) at marshal.c:  
440  
#12 0x0008d160 in w\_object (obj=23661220, arg=0xbfffe854, limit=1) at  
marshal.c:648  
#13 0x0008c9c8 in w\_obj\_each (id=1854980, value=23661220,  
arg=0xbf800678) at marshal.c:429  
#14 0x00056394 in foreach\_safe\_i (key=412980, value=3212837240,  
arg=0x1) at hash.c:131  
…

I gave up at:

#3525 0x0007756c in st\_foreach (table=0x2bae700, func=0x56360  
\<foreach\_safe\_i\>, arg=3213184664) at st.c:487

–  
Eric H. - removed\_email\_address@domain.invalid - [http://blog.segment7.net](http://blog.segment7.net)

I LIT YOUR GEM ON FIRE!

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**Author:** ![emmett](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/f0a364/32.png) [@emmett](https://www.ruby-forum.com/u/emmett)\
**Post date:** [December 9, 2006, 12:45pm UTC](https://www.ruby-forum.com/t/marshal-dump-error-on-powerbook-g4/78804/6 "2006-12-09T12:45:12Z")

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Tom P. wrote:

> Couldn’t you just use setrlimit() to bump up the maximum stack size?  
> At my day job, we’ve had to resort to that on a number of occasions on  
> different platforms.

We’ve once discussed on it([ruby-dev:_24405_]) and concluded that it’s  
not a well-doing for ignoring user’s purposely-specified stack limit.

If you really want to, Ruby has Process.setrlimit on both 1.8 and 1.9.  
Use them at your own risk.

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**Author:** ![emmett](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/f0a364/32.png) [@emmett](https://www.ruby-forum.com/u/emmett)\
**Post date:** [December 9, 2006, 6:10am UTC](https://www.ruby-forum.com/t/marshal-dump-error-on-powerbook-g4/78804/7 "2006-12-09T06:10:53Z")

</div>

On Dec 8, 2006, at 11:29 PM, Yukihiro M. wrote:

> Marshal uses recursion to traverse objects and OSX has far smaller  
> stack rlimits than other platforms. As a result of combination of  
> above, marshaling an object with long reference chain may cause  
> unexpected process termination. It is pretty diffucult to fix.

Couldn’t you just use setrlimit() to bump up the maximum stack size?  
At my day job, we’ve had to resort to that on a number of occasions  
on different platforms.

Cheers,

TomP