From: "Suraj N. Kurapati" <skurapat@...>
Date: 2006-04-17T08:40:21+09:00
Subject: Re: cross-thead violation - example code

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Suraj N. Kurapati wrote:
> {process:
> 	pthread_create();
> 	...
> 
> 	{pthread:
> 		ruby_init();
> 		...
> 		ruby_run();
> 	}
> 
> 	...
> 	rb_ary_new();  // causes cross-thread violation on rb_gc()
> }

Attached with this e-mail is example code for the above scenario. If
you un-comment the function-call to rb_ary_new() inside main(), then
the cross-thread violation does not occur.


Here is what happens when the scenario is compiled and run:

$ gcc -Wall -g -I$(ruby -rmkmf -e 'puts $topdir') \
- -l$(ruby -rmkmf -e 'puts CONFIG["RUBY_SO_NAME"]') \
- -lpthread ctviol.c -o ctviol

$ ./ctviol
[BUG] cross-thread violation on rb_gc()
ruby 1.8.4 (2005-12-24) [i486-linux]

Aborted (core dumped)


Here is the environment in which I ran the scenario:

$ ruby -v
ruby 1.8.4 (2005-12-24) [i486-linux]

$ uname -a
Linux yantram 2.6.15-20-386 #1 PREEMPT Tue Apr 4 17:48:51 UTC 2006
i686 GNU/Linux

$ ulimit -a
core file size          (blocks, -c) unlimited
data seg size           (kbytes, -d) unlimited
max nice                        (-e) unlimited
file size               (blocks, -f) unlimited
pending signals                 (-i) unlimited
max locked memory       (kbytes, -l) unlimited
max memory size         (kbytes, -m) unlimited
open files                      (-n) 1024
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) unlimited
max rt priority                 (-r) unlimited
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) unlimited
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited


Thanks for your consideration.
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/* Generates a cross-thread violation on rb_gc() under ruby 1.8.4 (2005-12-24) [i486-linux] */

#include <ruby.h>
#include <pthread.h>

void* ruby_run_handshake(void* dummy) {
	ruby_init();
	ruby_init_loadpath();

	ruby_run();	// this never returns
}

int main(int argc, char** argv) {
	// run a Ruby interpreter in the background
	pthread_t rubyThread;
	pthread_create(&rubyThread, 0, ruby_run_handshake, 0);


	// create some Ruby objects
	rb_ary_new();	// causes cross-thread violation on rb_gc()


	return 0;
}

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