A reduce stall at 0% implies that the map tasks are not outputting any records via the output collector. You need to go look at the task tracker and the task logs on all of your slave machines, to see if anything that seems odd appears in the logs. On the tasktracker web interface detail screen for your job, Are all of the map tasks finished Are any of the map tasks started Are there any Tasktracker nodes to service your job
On Sun, Feb 1, 2009 at 11:41 PM, Kwang-Min Choi <kmbest.c...@samsung.com>wrote: > I'm newbie in Hadoop. > and i'm trying to follow Hadoop Quick Guide at hadoop homepage. > but, there are some problems... > Downloading, unzipping hadoop is done. > and ssh successfully operate without password phrase. > > once... I execute grep example attached to Hadoop... > map task is ok. it reaches 100%. > but reduce task freezes at 0% without any error message. > I've waited it for more than 1 hour, but it still freezes... > same job in standalone mode is well done... > > i tried it with version 0.18.3 and 0.17.2.1. > all of them had same problem. > > could help me to solve this problem? > > Additionally... > I'm working on cloud-infra of GoGrid(Redhat). > So, disk's space & health is OK. > and, i've installed JDK 1.6.11 for linux successfully. > > > - KKwams >
