/**
* Attempt to find a handler to migrate to a new NonBlockingIOThread.
*
* @param imbalance describing a snapshot of NonBlockingIOThread load
* @return the handler to migrate to a new NonBlockingIOThread or null if no handler needs to be
* migrated.
*/
@Override
public MigratableHandler findHandlerToMigrate(LoadImbalance imbalance) {
Set<? extends MigratableHandler> candidates =
imbalance.getHandlersOwnerBy(imbalance.sourceSelector);
long migrationThreshold =
(long)
((imbalance.maximumEvents - imbalance.minimumEvents)
* MAXIMUM_NO_OF_EVENTS_AFTER_MIGRATION_COEFFICIENT);
MigratableHandler candidate = null;
long eventCountInSelectedHandler = 0;
for (MigratableHandler handler : candidates) {
long eventCount = imbalance.getEventCount(handler);
if (eventCount > eventCountInSelectedHandler) {
if (eventCount < migrationThreshold) {
eventCountInSelectedHandler = eventCount;
candidate = handler;
}
}
}
return candidate;
}
private void updateNewFinalImbalance() {
imbalance.minimumEvents = Long.MAX_VALUE;
imbalance.maximumEvents = Long.MIN_VALUE;
imbalance.sourceSelector = null;
imbalance.destinationSelector = null;
for (NonBlockingIOThread selector : ioThreads) {
long eventCount = selectorEvents.get(selector);
int handlerCount = selectorToHandlers.get(selector).size();
if (eventCount > imbalance.maximumEvents && handlerCount > 1) {
// if a selector has only 1 handle, there is no point in making it a source selector since
// there is no handler that can be migrated anyway. In that case it is better to move on to
// the next selector.
imbalance.maximumEvents = eventCount;
imbalance.sourceSelector = selector;
}
if (eventCount < imbalance.minimumEvents) {
imbalance.minimumEvents = eventCount;
imbalance.destinationSelector = selector;
}
}
}
