Steve Loughran created HADOOP-13525: ---------------------------------------
Summary: Optimize uses of FS operations in the ASF analysis frameworks, Key: HADOOP-13525 URL: https://issues.apache.org/jira/browse/HADOOP-13525 Project: Hadoop Common Issue Type: Sub-task Components: fs, fs/s3 Affects Versions: 2.7.2 Reporter: Steve Loughran Assignee: Steve Loughran Review uses of the FS APIs in applications using the Hadoop FS API to access filesystems; identify suboptimal uses and tune them for better performance against HDFS and object stores * Assume arbitrary Hadoop 2.x releases: make no changes which are known to make operations on older versions of Hadoop slower * Do propose those changes which deliver speedups in later versions of Hadoop, while not impacting older versions, or risk of causing scalability problems. * Add more tests, especially scalable ones which also display metrics. * Use standard benchmarks and optimization tools to identify hotspots. * Use FS behaviour as verified in the FS contract tests as evidence that filesystems correctly implement the Hadoop FS APIs. If a use of an API call is made which hints at the expectation of different/untested behaviours, leave alone and add new tests to the Hadoop FS contract to determine cross-FS semantics. * Focus on the startup, split calculation and directory scanning operations: the ones which slow down entire queries. * Eliminate use of {{isDirectory()}}, {{getLength()}}, {{exists()}} if a followon operation ({{getStatus()}},{{delete()}}, ... makes the use redundant. * Assume that {{FileStatus}} entries are not cached; the cost of creating them is 1 RPC call against HDFS, 1+ HTTPS call against object stores. * Locate calls to the listing operations, identify speedups, especially on recursive directory scans. * Identify suboptimal seek patterns (backwards as well as forwards) and attempt to reduce/eliminate through reordering and result caching. * Try to reuse the results of previous operations (e.g {{FileStatus}} instances) in follow-on calls. * Document best practises identified and implemented. -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: common-dev-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-dev-h...@hadoop.apache.org