# SystemStackError when rb\_define\_module\_function() \* 3 **URL:** \ **Category:** Ruby\ **Created:** [February 17, 2006, 5:14pm UTC](https://www.ruby-forum.com/t/systemstackerror-when-rb-define-module-function-3/69696 "2006-02-17T17:14:42Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![snk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/d9b06d/32.png) [@snk](https://www.ruby-forum.com/u/snk)\ **Post date:** [February 17, 2006, 5:14pm UTC](https://www.ruby-forum.com/t/systemstackerror-when-rb-define-module-function-3/69696/1 "2006-02-17T17:14:42Z")
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hello, I’m getting a “test.rb:46: stack level too deep (SystemStackError)” when defining three or more functions for a module, which is created & given to Ruby via the Ruby C API. The test.rb (actually “trunk/src/samp/test.rb”) file and the remaining source code is available in a Subversion repository here: svn checkout -r21 svn://rubyforge.org/var/svn/ruby-vpi - -or- [http://rubyforge.org/plugins/scmsvn/viewcvs.php/?root=ruby-vpi&pathrev=21](http://rubyforge.org/plugins/scmsvn/viewcvs.php/?root=ruby-vpi&pathrev=21) In particular, the error occurs when I register a third module function with Ruby C API inside line 25 of the file “trunk/src/RVPI.cin”: // register the VPI module RVPI\_\_rModuleDef = rb\_define\_module(“VPI”); rb\_define\_module\_function( // first func RVPI\_\_rModuleDef , “relay\_verilog” , RVPI\_rb\_relay\_verilog , 0 ); rb\_define\_module\_function( // second func RVPI\_\_rModuleDef , “register\_task” , RVPI\_rb\_register\_task , 1 ); rb\_define\_module\_function( // third func RVPI\_\_rModuleDef , “handle\_by\_name” , RVPI\_rb\_handle\_by\_name , 2 ); // FIXME: causes “stack level too deep (SystemStackError)” I originally thought the problem was with the third module function (named “RVPI\_rb\_handle\_by\_name”) that I was trying to register. But this was not the case, because the SystemStackError occurred even when I registered the first module function under a different name: // register the VPI module RVPI\_\_rModuleDef = rb\_define\_module(“VPI”); rb\_define\_module\_function( // first func RVPI\_\_rModuleDef , “relay\_verilog” , RVPI\_rb\_relay\_verilog , 0 ); rb\_define\_module\_function( // second func RVPI\_\_rModuleDef , “register\_task” , RVPI\_rb\_register\_task , 1 ); rb\_define\_module\_function( // first func with different name RVPI\_\_rModuleDef , “foo” , RVPI\_rb\_relay\_verilog , 0 ); What am I doing wrong? Thank you. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD4DBQFD9ULQmV9O7RYnKMcRAnzuAKCvyNqkSWWM3o7kpK1l2y8Xup98hACWOrGI qDsBxZ9L9CfILnHqlsLnaQ== =1Ilp -----END PGP SIGNATURE----- ---
**Author:** ![snk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/d9b06d/32.png) [@snk](https://www.ruby-forum.com/u/snk)\ **Post date:** [February 19, 2006, 1:55pm UTC](https://www.ruby-forum.com/t/systemstackerror-when-rb-define-module-function-3/69696/2 "2006-02-19T13:55:04Z")
Hi, In message “Re: SystemStackError when rb\_define\_module\_function() \* 3” on Sat, 18 Feb 2006 01:13:29 +0900, Suraj K. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) writes: |In particular, the error occurs when I register a third module |function with Ruby C API inside line 25 of the file |“trunk/src/RVPI.cin”: Did SystemStackError happened during rb\_define\_module\_function()? What OS are you using? There’s no explicit limitation for number of rb\_define\_module\_function() calls, except for OS resource limit. SystemStackError is caused when call stack is too deep, and the max depth is calculated in Init\_stack(). Since you are using embedded Ruby, you may fail to call Init\_stack() in the interpreter initialization. ``` matz. ``` ---
**Author:** ![snk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/d9b06d/32.png) [@snk](https://www.ruby-forum.com/u/snk)\ **Post date:** [February 19, 2006, 8:19pm UTC](https://www.ruby-forum.com/t/systemstackerror-when-rb-define-module-function-3/69696/3 "2006-02-19T20:19:08Z")
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Yukihiro M. wrote: > Did SystemStackError happened during rb\_define\_module\_function()? No, it happened later, when the Ruby interpreter was executing a script. > What OS are you using? Linux 2.6.12-10-386 #1 Mon Jan 16 17:18:08 UTC 2006 i686 GNU/Linux > Since you are using embedded Ruby, you may fail to call Init\_stack() > in the interpreter initialization. Ah, thank you. I tried putting a call to Init\_stack() in my initialization code but no luck. However, the problem is neither with embedded Ruby nor with my initialization of the Ruby interpreter: After some more investigation I happened upon the answer. There was indeed a heap/stack limitation upon the Ruby interpreter embedded in my C program! (my C program, inside its own process … unlimited stack space … (Ruby interpreter, inside a pthread … 2 MiB of stack space … ) ) I was using the pthread library, with default attribute values (thread stack size = 2 MiB) for pthread\_create(), to launch the Ruby interpreter. Naturally, the interpreter eventually ran out of stack space and produced the SystemStackError. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQFD+MOcmV9O7RYnKMcRAleEAJ4yC3X0OFEoEolyEsv1YNObj0MDBgCfSiJA sVF/m8hSVv9ZhEmlzwxamVE= =bVQ+ -----END PGP SIGNATURE----- ---
**Author:** ![snk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/d9b06d/32.png) [@snk](https://www.ruby-forum.com/u/snk)\ **Post date:** [February 24, 2006, 6:46pm UTC](https://www.ruby-forum.com/t/systemstackerror-when-rb-define-module-function-3/69696/4 "2006-02-24T18:46:18Z")
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Sorry, I forgot to specify the version of Ruby I am using: $ ruby --version ruby 1.8.3 (2005-06-23) [i486-linux] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQFD9UUbmV9O7RYnKMcRAku+AJ0fT6XGjoth4xxtUrzThHTTsCkhCwCeM6qT JdFhC9WTrGH9/iVtj9VBVOY= =jgf0 -----END PGP SIGNATURE-----