Strange interference between LSAPI, popen3 and MySQL

[andreas]

(I have cross-posted this question to ruby-lang: http://www.ruby-forum.com/topic/99988)

I am experiencing a very strange problem in my Rails app. I use popen3
to execute an external program. Everything works fine in Mongrel, but
when I use the app with LSAPI, after popen3 all MySQL queries fail with
"Mysql::Error (MySQL server has gone away)". Once I comment out popen3
it works fine again.

The problem is easy to reproduce in any Rails app using LSAPI and MySQL.
Add the following to a controller action:

require 'open3'
Open3.popen3('/usr/bin/ls') {|stdout, stdin, stderr| stdin.read }

The stdin.read is important.

[mistwang]

OK, we will take a closer look at this. Thanks for the bug report.

[andreas]

I could work around the MySQL problem, but popen3 does not work. I have posted some more information in this thread:
http://www.ruby-forum.com/topic/99988

[mistwang]

I found that MySQL connection will be lost even in Mongrel, so it is not a problem LSAPI specific.
As to popen3 not working, what kind of result is expected? seems I did not get any meaningful output under Mongrel as well.

[andreas]

Example: Open3.popen3('/bin/touch', '/tmp/popen3_is_OK'). It doesn't work when used from LSAPI.

[mistwang]

Ok, this issue is resolved, please check the updated thread
http://www.ruby-forum.com/topic/99988