Fix a hot loop in DirectExchangeClient #22039
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The fix changes queuedClients to LinkedHashSet, this helps with the filter condition in scheduleRequestIfNecessary. In addition two for loops are modified to become one loop on Iterator.
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Quick note about the performance regression -- what we observed was that on larger heavily-loaded clusters (hundreds of nodes), this became a severe issue causing cluster-wide degradation in performance. We've been running this fix on all of our clusters for 9+ months now and have seen full recovery to performance before 1ef4427 |
Have sent the completed CLA form to [email protected], waiting for the request to be reviewed and approved |
| @@ -73,7 +73,7 @@ public class DirectExchangeClient | |||
| private final Map<URI, HttpPageBufferClient> allClients = new ConcurrentHashMap<>(); | |||
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| @GuardedBy("this") | |||
| private final Deque<HttpPageBufferClient> queuedClients = new LinkedList<>(); | |||
| private final LinkedHashSet<HttpPageBufferClient> queuedClients = new LinkedHashSet<>(); | |||
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private final Set<HttpPageBufferClient> queuedClients = new LinkedHashSet<>();
| @@ -284,17 +284,22 @@ synchronized int scheduleRequestIfNecessary() | |||
| long projectedBytesToBeRequested = 0; | |||
| int clientCount = 0; | |||
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| for (HttpPageBufferClient client : queuedClients) { | |||
| Iterator<HttpPageBufferClient> queuedClientsIterator = queuedClients.iterator(); | |||
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nit: queuedClientsIterator -> clientIterator
| @@ -304,7 +309,7 @@ public ListenableFuture<Void> isBlocked() | |||
| } | |||
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| @VisibleForTesting | |||
| Deque<HttpPageBufferClient> getQueuedClients() | |||
| LinkedHashSet<HttpPageBufferClient> getQueuedClients() | |||
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Set<HttpPageBufferClient> getQueuedClients()
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Thanks @surajkn |
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Description
The fix changes queuedClients to LinkedHashSet, this helps with the filter condition in scheduleRequestIfNecessary. In addition two for loops are modified to become one loop on Iterator.
Additional context and related issues
We experienced some performance regression as a result of 1ef4427 and this is an attempt to fix the same.
Release notes
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