kishore gopalakrishna created HELIX-572:
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Summary: 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: 0.6.4, 0.7.1
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}
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