As I'm experiencing frequent crashes with mantra, I was wondering if there is a logfile somewhere (using Windows). I searched, but couldn't find any.

Mine have been saving to:
C:\Users\<YOURUSERNAME>\AppData\Local\Temp

To open temp Folder ,Another way is Simply type %temp% in the Run

Ok, cool. I found the logfile, the only problem is the information given in that file is very sparse.

As my renderings are crashing in a sort of unpredictable manner, I need some detailed render log files.

Is there any option I can tell mantra to write a detailed log with a high verbosity level, so I can debug what's going wrong?

In the Mantra Output Driver there are a couple things you can do.

In the Property > Statistics tab, change the verbosity to 5 to get maximum output. You can also set vex profiling on along with Python Tile Callbacks.

or

In the Main Tab render Command, add some flags to the mantra command. Use the option menu button to the right to see some default options. You can use:
mantra -V 5
and that is pretty much equivalent to the first option above.

Both of these will set mantra output to the console. On Linux/Mac, the commands would be echoed to the shell that was used to start the Houdini process.

You can also MMB on the Mantra ROP node to see the verbose output.

Another approach is to use the Performance Monitor pane.
If you enable the performance monitor along with the verbosity settings enabled on the ROP, you get all the information show up in the performance monitor window.


Hope that helps.