Hi there, mod_ruby no work with ITK-MPM!

I'm experimenting with the ITK MPM for Apache, available
from <http://home.samfundet.no/~sesse/mpm-itk/>. It is based on the
Prefork MPM; after a request is parsed, the process handling the
request changes user id to one specified in the config for the virtual
host.

mod_ruby no work with ITK-MPM (but prefork-mpm OK)! 

#ps -aux|grep httpd
I found a deadlocked httpd process, I don't know what's happens and I cannot be found any errors info in apache logs.

Can somebody help me? thanks in advance!

my apache config
----------------------------
<virtualhost xxxx>
    <IfModule itk.c>
        AssignUserID hao hao
    </IfModule>
    <IfModule mod_ruby.c>
        RubyRequire apache/ruby-run
        <Location /ruby>
            SetHandler ruby-object
            RubyHandler Apache::RubyRun.instance
            Options +ExecCGI
        </Location>
        <Files ~ (\.rbx$)>
            SetHandler ruby-object
            RubyHandler Apache::RubyRun.instance
        </Files>
    </IfModule>
</VirtualHost>
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