poorbarcode commented on code in PR #24833:
URL: https://github.com/apache/pulsar/pull/24833#discussion_r2487256099
##########
pulsar-broker/src/main/java/org/apache/pulsar/broker/service/ServerCnx.java:
##########
@@ -2610,6 +2581,93 @@ protected void
handleGetTopicsOfNamespace(CommandGetTopicsOfNamespace commandGet
}
}
+ private void internalHandleGetTopicsOfNamespace(String namespace,
NamespaceName namespaceName, long requestId,
+
CommandGetTopicsOfNamespace.Mode mode,
+ Optional<String>
topicsPattern, Optional<String> topicsHash,
+ Semaphore lookupSemaphore)
{
+ BooleanSupplier isPermitRequestCancelled = () ->
!ctx().channel().isActive();
+ TopicListSizeResultCache.ResultHolder
+ listSizeHolder =
service.getTopicListSizeResultCache().getTopicListSize(namespaceName.toString(),
mode);
+ listSizeHolder.getSizeAsync().thenAccept(initialSize -> {
+ maxTopicListInFlightLimiter.withAcquiredPermits(initialSize,
+ AsyncDualMemoryLimiter.LimitType.HEAP_MEMORY,
isPermitRequestCancelled, initialPermits -> {
+ return
getBrokerService().pulsar().getNamespaceService()
+ .getListOfUserTopics(namespaceName, mode)
+ .thenAccept(topics -> {
+ long actualSize =
TopicListMemoryLimiter.estimateTopicListSize(topics);
+ listSizeHolder.updateSize(actualSize);
+
maxTopicListInFlightLimiter.withUpdatedPermits(initialPermits, actualSize,
Review Comment:
I just want to throw an improvement: Instead of updating and acquiring
additional permits if the actual size is larger than estimated, we can skip
requesting the additional permits and just mark it as "beyond the original
value".
For example:
- max permits available: `100`
- estimated `100`
- acquire `100`
- get the real size `110`
- Apply directly without checking if the remaining permission is sufficient
- permits left: `-10`
---
- Benefit: An already applied 100 permits will not block subsequent requests
- Disadvantage: It has broken through the limitations
---
Anyway, I feel that the current implementation is also fine
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