[ https://issues.apache.org/jira/browse/HDFS-12130?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Tsz Wo Nicholas Sze updated HDFS-12130: --------------------------------------- Hadoop Flags: Reviewed +1 the 003 patch looks good. > 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 > Attachments: HDFS-12130.001.patch, HDFS-12130.002.patch, > HDFS-12130.003.patch > > > 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-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org