Appears to be related to volumetrics, as disabling them causes the render to complete successfully. I've also tested this on OS X and Windows, so it doesn't appear to be a platform-specific issue.

It looks like a problematic geometry. Disabling last bevel modifier is sufficient to render.

On one machine I tested I was using an Intel i7 3770K and on another an Intel i5 4288U.

so both are rendering on cpu

how long about is it getting "Stuck"

Forever - the last tile never finishes rendering and uses 100% CPU for the thread rendering the tile.

well i have completed the render could you try changing these settings

1. Auto detect threads instead of fixed
2. the order of rendering tiles
3. and what happens in the view port
4. also what GPU are you using

well i have completed the render could you try changing these settings

1. Auto detect threads instead of fixed
2. the order of rendering tiles
3. and what happens in the view port
4. also what GPU are you using

1. Same result; in fact it doesn't matter how many threads I use.
2. Tried 'Top to Bottom' - same result. It appears to get stuck on the same tile as when I use 'Center'.
3. In the viewport it gets stuck rendering the 6th sample and can't be stopped. If I make the viewport smaller, the number of samples I can render without freezing increases from 6 to about 10 or so.
4. This shouldn't be relevant - but I am using an NVIDIA GTX 460 on my 3770K system and the integrated GPU (Intel Iris 5100) on the 4288U.

Have tried rendering on cpu and gpu not at the same time of course

The render does not get stuck but the view does get stuck saying it is "paused"

is that a feature?

No, the viewport wasn't paused when I tested it; that's only how the file was saved. I can't render the scene on my GPU since it uses too much memory for my card. It'd be great if someone could test this on a GPU with more VRAM.

@ronan ducluzeau (zeauro) was able to reproduce the issue above, so I don't think it's just my setup.

can confirm but it happen when i tried to abort the render

If it can help, my CPU is an i7 4770K. I am under ubuntu 14.04 64 bits.

It is weird that it is not the same tile that freeze when I use official 2.73a and master 810c7ee.