Chen Liang created HDFS-12130: --------------------------------- Summary: Optimizing permission check for getContentSummary Key: HDFS-12130 URL: https://issues.apache.org/jira/browse/HDFS-12130 Project: Hadoop HDFS Issue Type: Improvement Components: namenode Reporter: Chen Liang Assignee: Chen Liang
Currently, {{getContentSummary}} takes two phases to complete: - phase1. check the permission of the entire subtree. If any subdirectory does not have {{READ_EXECUTE}}, an access control exception is thrown and {{getContentSummary}} terminates here (unless it's super user). - phase2. If phase1 passed, it will then traverse the entire tree recursively to get the actual content summary. An issue is, both phases currently hold the fs lock. Phase 2 has already been written that, it will yield the fs lock over time, such that it does not block other operations for too long. However phase 1 does not yield. Meaning it's possible that the permission check phase still blocks things for long time. One fix is to add lock yield to phase 1. But a simpler fix is to merge phase 1 into phase 2. Namely, instead of doing a full traversal for permission check first, we start with phase 2 directly, but for each directory, before obtaining its summary, check its permission first. This way we take advantage of existing lock yield in phase 2 code and still able to check permission and terminate on access exception. Thanks [~szetszwo] for the offline discussions! -- This message was sent by Atlassian JIRA (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-dev-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-dev-h...@hadoop.apache.org