hadoop-common-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Ted Dunning <tdunn...@veoh.com>
Subject Re: reducer outofmemoryerror
Date Thu, 24 Apr 2008 16:03:32 GMT

If these files are small, you will have a significant (but not massive) hit
in performance due to having so many files.


On 4/24/08 12:07 AM, "Arun C Murthy" <arunc@yahoo-inc.com> wrote:

> 
> On Apr 23, 2008, at 7:51 AM, Apurva Jadhav wrote:
> 
>> There are six reducers and 24000 mappers because there are 24000
>> files.
>> The number of tasks per node is 2.
>> mapred.child.java opts is the default value 200m. What is a good
>> value for this.? My mappers and reducers are fairly simple and do
>> not make large allocations.
> 
> Try upping that to 512M.
> 
> Arun
> 
>> Regards,
>> aj
>> 
>> Amar Kamat wrote:
>>> Apurva Jadhav wrote:
>>>> Hi,
>>>>  I have a 4 node hadoop 0.15.3 cluster. I am using the default
>>>> config files. I am running a map reduce job to process 40 GB log
>>>> data.
>>> How many maps and reducers are there? Make sure that there are
>>> sufficient number of reducers. Look at conf/hadoop-default.xml
>>> (see mapred.child.java.opts parameter) to change the heap settings.
>>> Amar
>>>> Some reduce tasks are failing with the following errors:
>>>> 1)
>>>> stderr
>>>> Exception in thread "org.apache.hadoop.io.ObjectWritable
>>>> Connection Culler" Exception in thread
>>>> "org.apache.hadoop.dfs.DFSClient$LeaseChecker@1b3f8f6"
>>>> java.lang.OutOfMemoryError: Java heap space
>>>> Exception in thread "IPC Client connection to /127.0.0.1:34691"
>>>> java.lang.OutOfMemoryError: Java heap space
>>>> Exception in thread "main" java.lang.OutOfMemoryError: Java heap
>>>> space
>>>> 
>>>> 2)
>>>> stderr
>>>> Exception in thread "org.apache.hadoop.io.ObjectWritable
>>>> Connection Culler" java.lang.OutOfMemoryError: Java heap space
>>>> 
>>>> syslog:
>>>> 2008-04-22 19:32:50,784 INFO org.apache.hadoop.mapred.ReduceTask:
>>>> task_200804212359_0007_r_000004_0 Merge of the 19 files in
>>>> InMemoryFileSystem complete. Local file is /data/hadoop-im2/
>>>> mapred/loca
>>>> l/task_200804212359_0007_r_000004_0/map_22600.out
>>>> 2008-04-22 20:34:16,012 INFO org.apache.hadoop.ipc.Client:
>>>> java.net.SocketException: Socket closed
>>>>        at java.net.SocketInputStream.read(SocketInputStream.java:
>>>> 162)
>>>>        at java.io.FilterInputStream.read(FilterInputStream.java:111)
>>>>        at org.apache.hadoop.ipc.Client$Connection$1.read
>>>> (Client.java:181)
>>>>        at java.io.BufferedInputStream.fill
>>>> (BufferedInputStream.java:218)
>>>>        at java.io.BufferedInputStream.read
>>>> (BufferedInputStream.java:235)
>>>>        at java.io.DataInputStream.readInt(DataInputStream.java:353)
>>>>        at org.apache.hadoop.ipc.Client$Connection.run(Client.java:
>>>> 258)
>>>> 
>>>> 2008-04-22 20:34:16,032 WARN
>>>> org.apache.hadoop.mapred.TaskTracker: Error running child
>>>> java.lang.OutOfMemoryError: Java heap space
>>>> 2008-04-22 20:34:16,031 INFO org.apache.hadoop.mapred.TaskRunner:
>>>> Communication exception: java.lang.OutOfMemoryError: Java heap space
>>>> 
>>>> Has anyone experienced similar problem ?   Is there any
>>>> configuration change that can help resolve this issue.
>>>> 
>>>> Regards,
>>>> aj
>>>> 
>>>> 
>>>> 
>>> 
>>> 
>> 
> 


Mime
View raw message