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https://issues.apache.org/jira/browse/GEODE-8195?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17118167#comment-17118167
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Bill Burcham commented on GEODE-8195:
-------------------------------------
It appears that this bug was introduced in GEODE-6977 which was part of the
1.10 release.
We will want to backport any fix to the 1.10 and later lines.
> ConcurrentModificationException from
> LocatorMembershipListenerImpl$DistributeLocatorsRunnable.run
> -------------------------------------------------------------------------------------------------
>
> Key: GEODE-8195
> URL: https://issues.apache.org/jira/browse/GEODE-8195
> Project: Geode
> Issue Type: Bug
> Components: membership
> Reporter: Bill Burcham
> Priority: Major
>
> this code in {{LocatorMembershipListenerImpl$DistributeLocatorsRunnable.run}}:
> {code}
> Set<LocatorJoinMessage> joinMessages = entry.getValue();
> for (LocatorJoinMessage locatorJoinMessage : joinMessages) {
> if (retryMessage(targetLocator, locatorJoinMessage, attempt)) {
> joinMessages.remove(locatorJoinMessage);
> } else {
> {code}
> modifies the {{joinMessages}} set as it is iterating over the set, resulting
> in a {{ConcurrentModificationException}}.
> This bug will cause notification of locators (of the presence of a new
> locator) to fail early if retry is necessary. If we have to retry notifying
> any locator, and we succeed, we’ll throw the
> {{ConcurrentModificationException}} and stop trying to notify any of the
> other locators.
> Here is a scratch file that illustrates the issue, throwing
> {{ConcurrentModificationException}}:
> {code}
> import java.util.HashSet;
> import java.util.Set;
> class Scratch {
> public static void main(String[] args) {
> final Set<String> joinMessages = new HashSet<>();
> joinMessages.add("one");
> joinMessages.add("two");
> for( final String entry:joinMessages ) {
> if (entry.equals("one"))
> joinMessages.remove(entry);
> }
> }
> }
> {code}
> From looking at the Geode code, {{joinMessages}} is not used outside the loop
> so there is no need to modify it at all—I think we can simply remove this
> line:
> {code}
> joinMessages.remove(locatorJoinMessage);
> {code}
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