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Posted to notifications@accumulo.apache.org by GitBox <gi...@apache.org> on 2021/02/10 23:19:47 UTC
[GitHub] [accumulo] ctubbsii opened a new issue #1924: SharedRateLimiterFactory.create() method does not correctly use WeakHashMap
ctubbsii opened a new issue #1924:
URL: https://github.com/apache/accumulo/issues/1924
**Describe the bug**
While looking at our use of WeakHashMap throughout our code, I observed that the SharedRateLimiterFactory uses a WeakHashMap called `activeLimiters`. However, it uses `activeLimiters.put(name, new SharedRateLImiter(name, ....))`, and the constructor stores a strong reference to `name` as a member variable. Therefore, it is impossible for `activeLimiters` to ever garbage collect and remove references once added.
**Versions (OS, Maven, Java, and others, as appropriate):**
- Affected version(s) of this project: 2.1.0-SNAPSHOT (probably others... only looked at this one)
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[GitHub] [accumulo] ctubbsii commented on issue #1924: SharedRateLimiterFactory.create() method does not correctly use WeakHashMap
Posted by GitBox <gi...@apache.org>.
ctubbsii commented on issue #1924:
URL: https://github.com/apache/accumulo/issues/1924#issuecomment-796396470
@DomGarguilo The `WeakHashMap` already uses weakly referenced keys. However, the objects in the value are strong references by default. The way to ensure the values in the hashmap don't retain strong references to the keys in the map is to wrap the values themselves in a `WeakReference`. So, instead of a `WeakHashMap<String,SharedRateLimiter>`, you would simply wrap the values and make them `WeakHashMap<String,WeakReference<SharedRateLimiter>>` instead. See the implementation note in the [`WeakHashMap` javadoc](https://docs.oracle.com/javase/8/docs/api/java/util/WeakHashMap.html) for a similar explanation.
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[GitHub] [accumulo] ctubbsii commented on issue #1924: SharedRateLimiterFactory.create() method does not correctly use WeakHashMap
Posted by GitBox <gi...@apache.org>.
ctubbsii commented on issue #1924:
URL: https://github.com/apache/accumulo/issues/1924#issuecomment-777802398
> > the constructor stores a strong reference to `name` as a member variable
>
> Which constructor are you referring to?
`new SharedRateLImiter`
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[GitHub] [accumulo] ctubbsii closed issue #1924: SharedRateLimiterFactory.create() method does not correctly use WeakHashMap
Posted by GitBox <gi...@apache.org>.
ctubbsii closed issue #1924:
URL: https://github.com/apache/accumulo/issues/1924
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[GitHub] [accumulo] DomGarguilo commented on issue #1924: SharedRateLimiterFactory.create() method does not correctly use WeakHashMap
Posted by GitBox <gi...@apache.org>.
DomGarguilo commented on issue #1924:
URL: https://github.com/apache/accumulo/issues/1924#issuecomment-777797567
> the constructor stores a strong reference to `name` as a member variable
Which constructor are you referring to?
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[GitHub] [accumulo] DomGarguilo commented on issue #1924: SharedRateLimiterFactory.create() method does not correctly use WeakHashMap
Posted by GitBox <gi...@apache.org>.
DomGarguilo commented on issue #1924:
URL: https://github.com/apache/accumulo/issues/1924#issuecomment-795644434
From what I can tell, there is no easy way to get this to work while using `WeakHashMap`. It seems the strong reference to `name` in `SharedRateLimiter` might be unavoidable. Maybe the best option is just to use `HashMap`.
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