Vinay created HDFS-5177:
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Summary: blocksScheduled count should be decremented for
abandoned blocks
Key: HDFS-5177
URL: https://issues.apache.org/jira/browse/HDFS-5177
Project: Hadoop HDFS
Issue Type: Bug
Components: namenode
Affects Versions: 2.1.0-beta, 3.0.0
Reporter: Vinay
DatanodeDescriptor#incBlocksScheduled() will be called for all datanodes of the
block on each allocation. But same should be decremented for abandoned blocks.
When one of the datanodes is down and same is allocated for the block along
with other live datanodes, then this block will be abandoned, but the scheduled
count on other datanodes will consider live datanodes as loaded, but in reality
these datanodes may not be loaded.
Anyway this scheduled count will be rolled every 20 mins.
Problem will come if the rate of creation of files is more. Due to increase in
the scheduled count, there might be chances of missing local datanode to write
to. and some times writes also can fail in small clusters.
So we need to decrement the unnecessary count on abandon block call.
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