[ https://issues.apache.org/jira/browse/HADOOP-17408?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Jim Brennan resolved HADOOP-17408. ---------------------------------- Fix Version/s: 3.4.0 3.3.1 Resolution: Fixed Thanks for the contribution [~ahussein] and [~daryn]! I have committed this to trunk and branch-3.3. The patch does not apply cleanly to branch-3.2 or earlier. Please provide a patch for 3.2 if desired. > Optimize NetworkTopology while sorting of block locations > --------------------------------------------------------- > > Key: HADOOP-17408 > URL: https://issues.apache.org/jira/browse/HADOOP-17408 > Project: Hadoop Common > Issue Type: Improvement > Components: common, net > Reporter: Ahmed Hussein > Assignee: Ahmed Hussein > Priority: Major > Labels: pull-request-available > Fix For: 3.3.1, 3.4.0 > > Time Spent: 1h 50m > Remaining Estimate: 0h > > In {{NetworkTopology}}, I noticed that there are some hanging fruits to > improve the performance. > Inside {{sortByDistance}}, collections.shuffle is performed on the list > before calling {{secondarySort}}. > {code:java} > Collections.shuffle(list, r); > if (secondarySort != null) { > secondarySort.accept(list); > } > {code} > However, in different call sites, {{collections.shuffle}} is passed as the > secondarySort to {{sortByDistance}}. This means that the shuffle is executed > twice on each list. > Also, logic wise, it is useless to shuffle before applying a tie breaker > which might make the shuffle work obsolete. > In addition, [~daryn] reported that: > * topology is unnecessarily locking/unlocking to calculate the distance for > every node > * shuffling uses a seeded Random, instead of ThreadLocalRandom, which is > heavily synchronized -- This message was sent by Atlassian Jira (v8.3.4#803005) --------------------------------------------------------------------- To unsubscribe, e-mail: common-dev-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-dev-h...@hadoop.apache.org