Comment 4 for bug 338344

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Daniel Nurmi (nurmi) wrote : Re: Node controller sometimes crashes

I have discovered the reason behind this behavior. The node controller (an axis2 web service that is loaded and run by an apache2 thread) can only run as a single thread. This means that apache2 must be configured to only start one child (or thread) to run the NC. While we set up the NC's httpd.conf to limit the number of threads that apache will spawn to 1, there is one apache2 flavor that doesn't honor this configuration - apache2-itk.

So, the problem is not that a single NC is crashing, but that multiple NCs are starting that grabbing semaphores, creating a deadlock situation.

The solution is to install the 'non itk' version of apache2. We encountered this problem once, and the simple solution was 'shut down NC, apt-get install apache2, start up NC'.

is there a way to make sure that apache2-itk does not satisfy the node controller's dependency on 'apache2' for a more permanent fix? alternatively, is there a way to limit the number of threads that apache2-itk will spawn (we have thus far been unable to find a way to do this)? Either should solve the problem long-term, but we have not fully tested apache2-itk and so would posit that the former is preferable.