where does the temporary task directory get created in mapred?

[Koert Kuipers <ko...@tresata.com>]

i was looking at
org.apache.hadoop.mapreduce.lib.output.FileOutputCommitter's setupTask
method, but it does nothing and states:

    // FileOutputCommitter's setupTask doesn't do anything. Because the
    // temporary task directory is created on demand when the
    // task is writing.

ok i got that. but then where is the temporary task then created "on demand
when the task is writing"? i looked all over the OutputCommitters,
RecordWriters, OutputFormats, but i cannot find it. i must have overlooked
it...

can someone please point me to the relevant class/method? thank you so much!

best, koert