Github user satishd commented on a diff in the pull request:
https://github.com/apache/storm/pull/2218#discussion_r128991661
--- Diff:
storm-client/src/jvm/org/apache/storm/topology/base/BaseStatefulWindowedBolt.java
---
@@ -151,6 +158,38 @@
return this;
}
+ /**
+ * If set, the stateful windowed bolt would use the backend state for
window persistence and
+ * only keep a sub-set of events in memory as specified by {@link
#withMaxEventsInMemory(long)}.
+ */
+ public BaseStatefulWindowedBolt<T> withPersistence() {
+ persistent = true;
+ return this;
+ }
+
+ /**
+ * The maximum number of window events to keep in memory. This is
meaningful only if
+ * {@link #withPersistence()} is also set. As the number of events in
memory grows close
+ * to the maximum, the events that are less likely to be used again
are evicted and persisted.
+ * The default value for this is {@code 1,000,000}.
+ *
+ * @param maxEventsInMemory the maximum number of window events to
keep in memory
+ */
+ public BaseStatefulWindowedBolt<T> withMaxEventsInMemory(long
maxEventsInMemory) {
--- End diff --
We can explore later limiting with memory size as that would give better
handle to the user on memory resources, which can be with onheap/offheap cache.
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