[Hadoop-common-user] fair scheduler preemptions timeout difficulties

Greetings, Hadoop Fans:

I'm attempting to use the timeout feature of the Fair Scheduler (using
Cloudera's most recently released distribution 0.20.1+152-1), but without
success. I'm using the following configs:

/etc/hadoop/conf/mapred-site.xml

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<configuration>
<property>
<name>mapred.job.tracker</name>
<value>hadoop-master:8021</value>
</property>
<property>
<name>mapred.tasktracker.map.tasks.maximum</name>
<value>9</value>
</property>
<property>
<name>mapred.tasktracker.reduce.tasks.maximum</name>
<value>3</value>
</property>
<property>
<name>mapred.jobtracker.taskScheduler</name>
<value>org.apache.hadoop.mapred.FairScheduler</value>
</property>
<property>
<name>mapred.fairscheduler.allocation.file</name>
<value>/etc/hadoop/conf/pools.xml</value>
</property>
<property>
<name>mapred.fairscheduler.assignmultiple</name>
<value>true</value>
</property>
<property>
<name>mapred.fairscheduler.poolnameproperty</name>
<value>pool.name</value>
</property>
<property>
<name>pool.name</name>
<value>default</value>
</property>

</configuration>

and /etc/hadoop/conf/pools.xml

<?xml version="1.0"?>
<allocations>
<pool name="realtime">
<minMaps>4</minMaps>
<minReduces>1</minReduces>
<minSharePreemptionTimeout>180</minSharePreemptionTimeout>
<weight>2.0</weight>
</pool>
<pool name="default">
<minMaps>2</minMaps>
<minReduces>2</minReduces>
<maxRunningJobs>1</maxRunningJobs>
</pool>
</allocations>

but a job in the realtime pool fails to interrupt a job running in the
default queue (waited for > 15 minutes). Is there something wrong with my
configs? Or is there anything in the logs that would be useful for
debugging? (I've only found a "successfully configured fairscheduler"
comment in the jobtracker log upon starting up the daemon.)

Help would be extremely appreciated!

Thanks,
-James Warren