zhengchenyu commented on code in PR #4127:
URL: https://github.com/apache/hadoop/pull/4127#discussion_r893040886
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hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/resolver/MembershipNamenodeResolver.java:
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@@ -371,24 +405,37 @@ private List<MembershipState>
getRecentRegistrationForQuery(
membershipStore.getNamenodeRegistrations(request);
List<MembershipState> memberships = response.getNamenodeMemberships();
- if (!addExpired || !addUnavailable) {
- Iterator<MembershipState> iterator = memberships.iterator();
- while (iterator.hasNext()) {
- MembershipState membership = iterator.next();
- if (membership.getState() == EXPIRED && !addExpired) {
- iterator.remove();
- } else if (membership.getState() == UNAVAILABLE && !addUnavailable) {
- iterator.remove();
- }
+ List<MembershipState> observerMemberships = new ArrayList<>();
+ Iterator<MembershipState> iterator = memberships.iterator();
+ while (iterator.hasNext()) {
+ MembershipState membership = iterator.next();
+ if (membership.getState() == EXPIRED && !addExpired) {
+ iterator.remove();
+ } else if (membership.getState() == UNAVAILABLE && !addUnavailable) {
+ iterator.remove();
+ } else if (membership.getState() == OBSERVER && observerRead) {
+ iterator.remove();
+ observerMemberships.add(membership);
}
}
- List<MembershipState> priorityList = new ArrayList<>();
- priorityList.addAll(memberships);
- Collections.sort(priorityList, new NamenodePriorityComparator());
+ if(!observerRead) {
+ Collections.sort(memberships, new NamenodePriorityComparator());
+ LOG.debug("Selected most recent NN {} for query", memberships);
+ return memberships;
+ } else {
+ List<MembershipState> ret = new ArrayList<>(
+ memberships.size() + observerMemberships.size());
+ Collections.sort(memberships, new NamenodePriorityComparator());
+ if(observerMemberships.size() > 1) {
+ Collections.shuffle(observerMemberships);
Review Comment:
I think recently means the latest observer namenode set from
MembershipState. Then disperse queries by shuffle.
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