Yi Liu created HDFS-6871:
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Summary: Improve NameNode performance when creating file
Key: HDFS-6871
URL: https://issues.apache.org/jira/browse/HDFS-6871
Project: Hadoop HDFS
Issue Type: Improvement
Components: namenode, performance
Reporter: Yi Liu
Assignee: Yi Liu
Priority: Critical
Fix For: 2.6.0
Creating file with overwrite flag will cause NN fall into flush edit logs and
block other requests if the file exists.
When we create a file with overwrite flag (default is true) in HDFS, NN will
remove original file if it exists. In FSNamesystem#startFileInternal, NN
already holds the write lock, it calls {{deleteInt}} if the file exists, there
is logSync in {{deleteInt}}. So in this case, logSync is under write lock, it
will heavily affect the NN performance.
We should ignore the force logSync in {{deleteInt}} in this case.
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