The program "mrbench" takes 1 second on a single node, so I think waiting
for 1 minute should be long enough. And I also restarted Hadoop after I
updated the config file.
Yunhong
On Fri, 18 Jan 2008, Miles Osborne wrote:
I think it takes a while to actually work, so be patient!
Miles
On 18/01/2008, Yunhong Gu1 <[EMAIL PROTECTED]> wrote:
Hi, Miles,
Thanks for your information. I applied this but the problem still exists.
By the way, when this happens, the CPUs are idle and doing nothing.
Yunhong
On Fri, 18 Jan 2008, Miles Osborne wrote:
I had the same problem. If I recall, the fix is to add the following to
your hadoop-site.xml file:
<property>
<name>mapred.reduce.copy.backoff</name>
<value>5</value>
</property>
See hadoop-1984
Miles
On 18/01/2008, Yunhong Gu1 <[EMAIL PROTECTED]> wrote:
Hi,
If someone knows how to fix the problem described below, please help me
out. Thanks!
I am testing Hadoop on 2-node cluster and the "reduce" always hangs at
some stage, even if I use different clusters. My OS is Debian Linux
kernel
2.6 (AMD Opteron w/ 4GB Mem). Hadoop verision is 0.15.2. Java version
is
1.5.0_01-b08.
I simply tried "./bin/hadoop jar hadoop-0.15.2-test.jar mrbench" and
when
the map stage finishes, the reduce stage will hang somewhere in the
middle, sometimes at 0%. I also tried any other mapreduce program I can
find in the example jar package but they all hang.
The log file simply print
2008-01-18 15:15:50,831 INFO org.apache.hadoop.mapred.TaskTracker:
task_200801181424_0004_r_000000_0 0.0% reduce > copy >
2008-01-18 15:15:56,841 INFO org.apache.hadoop.mapred.TaskTracker:
task_200801181424_0004_r_000000_0 0.0% reduce > copy >
2008-01-18 15:16:02,850 INFO org.apache.hadoop.mapred.TaskTracker:
task_200801181424_0004_r_000000_0 0.0% reduce > copy >
forever.
The program does work if I start Hadoop only on single node.
Below is my hadoop-site.xml configuration:
<configuration>
<property>
<name>fs.default.name</name>
<value>10.0.0.1:60000</value>
</property>
<property>
<name>mapred.job.tracker</name>
<value>10.0.0.1:60001</value>
</property>
<property>
<name>dfs.data.dir</name>
<value>/raid/hadoop/data</value>
</property>
<property>
<name>mapred.local.dir</name>
<value>/raid/hadoop/mapred</value>
</property>
<property>
<name>hadoop.tmp.dir</name>
<value>/raid/hadoop/tmp</value>
</property>
<property>
<name>mapred.child.java.opts</name>
<value>-Xmx1024m</value>
</property>
<property>
<name>mapred.tasktracker.tasks.maximum</name>
<value>4</value>
</property>
<!--
<property>
<name>mapred.map.tasks</name>
<value>7</value>
</property>
<property>
<name>mapred.reduce.tasks</name>
<value>3</value>
</property>
-->
<property>
<name>fs.inmemory.size.mb</name>
<value>200</value>
</property>
<property>
<name>dfs.block.size</name>
<value>134217728</value>
</property>
<property>
<name>io.sort.factor</name>
<value>100</value>
</property>
<property>
<name>io.sort.mb</name>
<value>200</value>
</property>
<property>
<name>io.file.buffer.size</name>
<value>131072</value>
</property>
</configuration>
