Re: nutch crawldb failed for java heap space

>  Hi,everyone, these days a  nutch problem occur to me when I test nutch to
> index 2 millions pages.
>
> When then program steps into the reduce stage of crawldb update, the error
> messeges gives as below:
> Before this test, I try to crawl and index 1 millions pages, nutch goes
> well.
> I alter  the HADOOP_HEAPSIZE  in the hadoop-env.sh,  1000m,2000m, even  to
> my memory size 6GB, but make no different. And change the value of
>  properties "mapred.child.java.opts" by 200m, 1000m, 2000m,4000m,~ 6GB time
> and again , but it seems no difference.
>
> I have 9 machines(CPU core 2 2.8GHZ, 6GB RAM,) , 1 master ,and 8
> slaves(tasktrack).
> I attach the hadoop-env.sh and hadoop-site.xml files after this
> messege, appreciate your help very much.
> ============================================================
>
> java.lang.OutOfMemoryError: GC overhead limit exceeded
>        at java.util.HashMap.<init>(HashMap.java:209)
>        at org.apache.hadoop.io.MapWritable.<init>(MapWritable.java:43)
>        at org.apache.nutch.crawl.CrawlDatum.readFields(CrawlDatum.java:260)
>        at
>
> org.apache.hadoop.io.serializer.WritableSerialization$WritableDeserializer.deserialize(WritableSerialization.java:67)
>        at
>
> org.apache.hadoop.io.serializer.WritableSerialization$WritableDeserializer.deserialize(WritableSerialization.java:40)
>        at
> org.apache.hadoop.mapred.Task$ValuesIterator.readNextValue(Task.java:940)
>        at org.apache.hadoop.mapred.Task$ValuesIterator.next(Task.java:880)
>        at
>
> org.apache.hadoop.mapred.ReduceTask$ReduceValuesIterator.moveToNext(ReduceTask.java:237)
>        at
>
> org.apache.hadoop.mapred.ReduceTask$ReduceValuesIterator.next(ReduceTask.java:233)
>        at
> org.apache.nutch.crawl.CrawlDbReducer.reduce(CrawlDbReducer.java:70)
>        at
> org.apache.nutch.crawl.CrawlDbReducer.reduce(CrawlDbReducer.java:35)
>        at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:436)
>        at org.apache.hadoop.mapred.Child.main(Child.java:158)
>
>
> java.lang.OutOfMemoryError: Java heap space
>        at
> java.util.concurrent.locks.ReentrantLock.<init>(ReentrantLock.java:234)
>        at
>
> java.util.concurrent.ConcurrentHashMap$Segment.<init>(ConcurrentHashMap.java:289)
>        at
> java.util.concurrent.ConcurrentHashMap.<init>(ConcurrentHashMap.java:613)
>        at
> java.util.concurrent.ConcurrentHashMap.<init>(ConcurrentHashMap.java:652)
>        at
>
> org.apache.hadoop.io.AbstractMapWritable.<init>(AbstractMapWritable.java:46)
>        at org.apache.hadoop.io.MapWritable.<init>(MapWritable.java:42)
>        at org.apache.hadoop.io.MapWritable.<init>(MapWritable.java:52)
>        at org.apache.nutch.crawl.CrawlDatum.set(CrawlDatum.java:321)
>        at
> org.apache.nutch.crawl.CrawlDbReducer.reduce(CrawlDbReducer.java:96)
>        at
> org.apache.nutch.crawl.CrawlDbReducer.reduce(CrawlDbReducer.java:35)
>        at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:436)
>        at org.apache.hadoop.mapred.Child.main(Child.java:158)
>
> =====================================================================
> hadoop-env.sh
>
> # Set Hadoop-specific environment variables here.
> # The only required environment variable is JAVA_HOME.  All others are
> # optional.  When running a distributed configuration it is best to
> # set JAVA_HOME in this file, so that it is correctly defined on
> # remote nodes.
> # The java implementation to use.  Required.
> # export JAVA_HOME=/usr/lib/j2sdk1.5-sun
> export JAVA_HOME=/usr/lib/jvm/java-6-sun
> export HADOOP_HOME=/home/had/nutch-1.0
> export HADOOP_CONF_DIR=/home/had/nutch-1.0/conf
> export HADOOP_LOG_DIR=/home/had/nutch-1.0/logs
> export NUTCH_HOME=/home/had/nutch-1.0
> export NUTCH_CONF_DIR=/home/had/nutch-1.0/conf
> # Extra Java CLASSPATH elements.  Optional.
> # export HADOOP_CLASSPATH=
> # The maximum amount of heap to use, in MB. Default is 1000.
> export HADOOP_HEAPSIZE=4000
> export NUTCH_HEAPSIZE=4000
>
> ==========================================================================
>
> hadoop-site.xml
>
> <?xml version="1.0"?>
> <?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
> <!-- Put site-specific property overrides in this file. -->
> <configuration>
> <property>
>  <name>fs.default.name</name>
>  <value>hdfs://distributed1:9000/</value>
>  <description>The name of the default file system. Either the literal
> string "local" or a host:port for DFS.</description>
> </property>
> <property>
>  <name>mapred.job.tracker</name>
>  <value>distributed1:9001</value>
>  <description>The host and port that the MapReduce job tracker runs at. If
> "local", then jobs are run in-process as a single map and reduce
> task.</description>
> </property>
> <property>
>  <name>mapred.tasktracker.tasks.maximum</name>
>  <value>2</value>
>  <description>
>    The maximum number of tasks that will be run simultaneously by
>    a task tracker. This should be adjusted according to the heap size
>    per task, the amount of RAM available, and CPU consumption of each task.
>  </description>
> </property>
> <property>
>  <name>mapred.map.tasks</name>
>  <value>799</value>
>  <description>
>    This should be a prime number larger than multiple number of slave
> hosts,
>    e.g. for 3 nodes set this to 17
>  </description>
> </property>
> <property>
>  <name>io.file.buffer.size</name>
>  <value>131072</value>(test  set this value to 4096, but make no
> difference)
>  <description>The size of buffer for use in sequence files.
>  The size of this buffer should probably be a multiple of hardware
>  page size (4096 on Intel x86), and it determines how much data is
>  buffered during read and write operations.</description>
> </property>
> <property>
>  <name>mapred.reduce.tasks</name>
>  <value>29</value>
>  <description>
>    This should be a prime number close to a low multiple of slave hosts,
>    e.g. for 3 nodes set this to 7
>  </description>
> </property>
>
> <property>
>  <name>hadoop.tmp.dir</name>
>  <value>/home/had/nutch-1.0/tmp</value>
>  <description>A base for other temporary directories.</description>
> </property>
> <property>
>  <name>dfs.name.dir</name>
>  <value>/home/had/nutch-1.0/filesystem/name</value>
>  <description>Determines where on the local filesystem the DFS name node
> should store the name table. If this is a comma-delimited list of
> directories then the name table is replicated in all of the directories,
> for
> redundancy. </description>
> </property>
> <property>
>  <name>dfs.data.dir</name>
>  <value>/home/had/nutch-1.0/filesystem/data</value>
>  <description>Determines where on the local filesystem an DFS data node
> should store its blocks. If this is a comma-delimited list of directories,
> then data will be stored in all named directories, typically on different
> devices. Directories that do not exist are ignored.</description>
> </property>
> <property>
>  <name>dfs.replication</name>
>  <value>1</value>
>  <description>Default block replication. The actual number of replications
> can be specified when the file is created. The default is used if
> replication is not specified in create time.</description>
> </property>
> <property>
>  <name>mapred.child.java.opts</name>
>  <value>-Xmx1000m</value>
>  <description>
>    You can specify other Java options for each map or reduce task here,
>    but most likely you will want to adjust the heap size.
>  </description>
> </property>
> <property>
>  <name>mapred.system.dir</name>
>  <value>/home/had/nutch-1.0/filesystem/mapreduce/system</value>
> </property>
> <property>
>  <name>mapred.local.dir</name>
>  <value>/home/had/nutch-1.0/filesystem/mapreduce/local</value>
> </property>
>
> </configuration>
> ====================================================================
>