Uma Maheswara Rao G created HDFS-4526:
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Summary: If persistBlocks enabled in Namenode, hflush call can
avoid persisting blocks with fsync
Key: HDFS-4526
URL: https://issues.apache.org/jira/browse/HDFS-4526
Project: Hadoop HDFS
Issue Type: Bug
Components: namenode
Affects Versions: 2.0.3-alpha, 3.0.0
Reporter: Uma Maheswara Rao G
Assignee: Uma Maheswara Rao G
If persists blocks enabled/in HA, evenry getAdditionalBlock will persist the
blocks.
So, if user calls Hflush, then client can simply ensure data flushed to DNs and
need not worry about fsync.
Since we can not depend upon client side configuration about persistBlocks, we
can just make a fsync call to NN and check whether persistBlocks enabled. If it
is enabled, then simply return as it would have already persisted. So, that
below peice of code execution can be avoided for every blocks and hflush calls
from fsync:
{code}
writeLock();
try {
checkOperation(OperationCategory.WRITE);
if (isInSafeMode()) {
throw new SafeModeException("Cannot fsync file " + src, safeMode);
}
INodeFileUnderConstruction pendingFile = checkLease(src, clientName);
dir.persistBlocks(src, pendingFile);
} finally {
writeUnlock();
}
getEditLog().logSync();
{code}
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