We should document this somewhere. It is not intuitive as you mention.
On 12/17/11 1:41 AM, Sebastian Schelter wrote:
A small hint for everyone who wants to run giraph's unit tests on a
pseudo-distributed single node hadoop cluster:
You have to adjust the configuration to allow 4 concurrent map tasks per
node (default in hadoop-0.20.203 is 2), otherwise the tests will fail!
You have to adjust mapred.tasktracker.map.tasks.maximum and
mapred.map.tasks in mapred-site.xml. Took me a while to figure out :)