[
https://issues.apache.org/jira/browse/HELIX-572?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14351965#comment-14351965
]
kishore gopalakrishna commented on HELIX-572:
---------------------------------------------
For now, I will submit a patch to not delete the external view. I am assuming
the reason we were deleting earlier was to handle the change in number of
buckets dynamically. I dont think we can support changing them dynamically. We
will have to re visit that again.
> External view is recreated every time for bucketized resource
> -------------------------------------------------------------
>
> Key: HELIX-572
> URL: https://issues.apache.org/jira/browse/HELIX-572
> Project: Apache Helix
> Issue Type: Bug
> Components: helix-core
> Affects Versions: 0.7.1, 0.6.4
> Reporter: kishore gopalakrishna
> Assignee: kishore gopalakrishna
> Priority: Critical
> Fix For: 0.6.5, 0.7.2
>
>
> If the resource is bucketized, controller first deletes the existing external
> view and then recreates it. First of all this is inefficient and triggers a
> lot of unwanted changes.
> The code is i here ZKHelixDataAccessor
> {code}
> case EXTERNALVIEW:
> if (value.getBucketSize() == 0) {
> records.add(value.getRecord());
> } else {
> _baseDataAccessor.remove(path, options);
> {code}
> Second, the external view change listeners stops listening to further
> changes. This may or may not happen all the time, but the probability of
> occurrence is pretty high.
> After EV is deleted, the listener gets a callback. The callback is handled by
> zkcallbackhandler. When it gets a callback, it tries to set the watch again
> but the path may or may not exist (depending on how fast the controller
> recreated the external view). If the path exists there is not problem, but if
> it does not, we assume that the parent node is deleted and remove the
> listener and invoke FINALIZE. Again this would not have happened if the
> resource was not bucketized.
> {code}
> @Override
> public void handleChildChange(String parentPath, List<String>
> currentChilds) {
> try {
> updateNotificationTime(System.nanoTime());
> if (parentPath != null && parentPath.startsWith(_path)) {
> NotificationContext changeContext = new NotificationContext(_manager);
> if (currentChilds == null) {
> // parentPath has been removed
> if (parentPath.equals(_path)) {
> // _path has been removed, remove this listener
> _manager.removeListener(_propertyKey, _listener);
> }
> changeContext.setType(NotificationContext.Type.FINALIZE);
> } else {
> changeContext.setType(NotificationContext.Type.CALLBACK);
> }
> changeContext.setPathChanged(_path);
> invoke(changeContext);
> }
> } catch (Exception e) {
> String msg =
> "exception in handling child-change. instance: " + _instanceName +
> ", parentPath: "
> + parentPath + ", listener: " + _listener;
> ZKExceptionHandler.getInstance().handle(msg, e);
> }
> {code}
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
