"GC Overhead limit exceeded" on Hadoop .20 datanode
garbage-collection, hadoop
Solution
Try to increase the memory for datanode by using this: (hadoop restart required for this to work)
export HADOOP_DATANODE_OPTS="-Xmx10g"
This will set the heap to 10gb...you can increase as per your need.
You can also paste this at the start in `$HADOOP_CONF_DIR/hadoop-env.sh` file.
Problem
I've searched and not finding much information related to Hadoop Datanode processes dying due to GC overhead limit exceeded, so I thought I'd post a question. We are running a test where we need to confirm our Hadoop cluster can handle having ~3million files stored on it (currently a 4 node cluster). We are using a 64bit JVM and we've allocated 8g to the namenode. However, as my test program writes more files to DFS, the datanodes start dying off with this error: Exception in thread "DataNode: [/var/hadoop/data/hadoop/data]" java.lang.OutOfMemoryError: GC overhead limit exceeded I saw some posts about some options (parallel GC?) I guess which can be set in hadoop-env.sh but I'm not too sure of the syntax and I'm kind of a newbie, so I didn't quite grok how it's done. Thanks for any help here!