As the business continues to grow, the amount of data stored in the cluster hadoop also increasing the amount of data will appear in the PB level hadoop / hdfs command performs slowly or does not return a result and GC errors;
You need to adjust the size parameters HADOOP_HEAPSIZE; 1000MB the default parameter;
The actual situation:
Data amount 1PB, HADOOP_HEAPSIZE parameter is set to 16GB, the results can be returned to normal.
Adjusted according to actual situation and ensure hadoop / hdfs normal command such as return results.