getAsync(“key”).get(timeout, sec) doesn't wait, return null

问题

Hazelcast 3.4.4. I got a situation when map.getAsync returns null no matter what. It even if timeout set to 10000000, TimeUnit.SECONDS it doesn't wait.

But if I put Thread.sleep(10000) just before getAsync then it returns proper value from the map.

I wonder what's wrong and how I could check/fix/undersand it?

UPDATE: if I remove import ExecutionContext.Implicit.global from my code and all dependencies (like Scala.concurent.Future), then getAsync starts working again. But I'm not satisfied still ...

回答1:

To me it feels like you expect it to wait until a value is put into the map, doesn't it?

It doesn't mean that it will wait until a value becomes available, it just gives you the option to have a timeout for the case the cluster is totally exhausted and cannot answer your request fast enough.

I actually think there is no good way to achieve what you're looking for but you could use the local EntryListeners, waiting for a key and forward the event through a topic, if that makes sense. You might also need a Promise kind of implementation.

回答2:

Not sure if it's an issue with 3.4.4, but 3.5.1 works (from REPL):

scala> import scala.concurrent._
import scala.concurrent._

scala> import ExecutionContext.Implicits.global
import ExecutionContext.Implicits.global

scala> val map = hz.getMap[String, Int]("map")
map: com.hazelcast.core.IMap[String,Int] = IMap{name='map'}

scala> map.set("one", 1)

scala> map.getAsync("one").get()
res4: Int = 1

来源：https://stackoverflow.com/questions/31974762/getasynckey-gettimeout-sec-doesnt-wait-return-null

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