Ravi Prakash created HDFS-8344:
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Summary: NameNode doesn't recover lease for files with missing
blocks
Key: HDFS-8344
URL: https://issues.apache.org/jira/browse/HDFS-8344
Project: Hadoop HDFS
Issue Type: Bug
Components: namenode
Affects Versions: 2.7.0
Reporter: Ravi Prakash
Assignee: Ravi Prakash
I found another\(?) instance in which the lease is not recovered. This is
reproducible easily on a pseudo-distributed single node cluster
# Before you start it helps if you set. This is not necessary, but simply
reduces how long you have to wait
{code}
public static final long LEASE_SOFTLIMIT_PERIOD = 30 * 1000;
public static final long LEASE_HARDLIMIT_PERIOD = 2 *
LEASE_SOFTLIMIT_PERIOD;
{code}
# Client starts to write a file. (could be less than 1 block, but it hflushed
so some of the data has landed on the datanodes) (I'm copying the client code I
am using. I generate a jar and run it using $ hadoop jar TestHadoop.jar)
# Client crashes. (I simulate this by kill -9 the $(hadoop jar TestHadoop.jar)
process after it has printed "Wrote to the bufferedWriter"
# Shoot the datanode. (Since I ran on a pseudo-distributed cluster, there was
only 1)
I believe the lease should be recovered and the block should be marked missing.
However this is not happening. The lease is never recovered.
The effect of this bug for us was that nodes could not be decommissioned
cleanly. Although we knew that the client had crashed, the Namenode never
released the leases (even after restarting the Namenode) (even months
afterwards). There are actually several other cases too where we don't consider
what happens if ALL the datanodes die while the file is being written, but I am
going to punt on that for another time.
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