Efficient way to clear TreeCache?

[mudiobada]

Hello everyone,

we had a situation where network issues caused Infinispan TreeCache to become unacceptably slow.

The scenario was one where a replicated cache needed to be initialize from external storage.

Analysis of the problem showed that treeCache.getRoot().removeChildren() was particularly slow

(even with IGNORE_RETURN_VALUES and SKIP_LOCKING flags).

Question: Is there a more efficient way to clear a TreeCache?

Notes:

  *) We are using Infinispan 5.2.15 on JBoss EAP 6.4

  *) The cache in obtained from the JBoss infinispan subsystem so recreating the underlying Cache and TreeCache is not desirable.

  *) I tried the following hack that exploits Cache.clear() and the internal implementation details of TreeCacheFactory and TreeCacheImpl (up till 8.0):

       treeCache.getCache().clear(); // Empty the cache with ClearCommand

       (void) TreeCacheFactory.createTreeCache(treeCache); // Recreate the root nodes

     It gave the kind of performance that would be desirable when a TreeCache needs to be cleared.

I would appreciate your advice.

Thanks.

[nadirx]

The semantics of cache.clear()  were changed in 7.2.0.Final [ISPN-5370] Make clear() non-transactional and lock free - JBoss Issue Tracker.

The same concepts were not transposed to the Tree cache. Probably an equivalent TreeCache.clear() method (which would essentially do what you describe above) would be useful.

[mudiobada]

Thanks for pointing out situation and the newer semantics in 7.2.

The implementation you outlined that follows the semantics of Cache.clear() would definitely be appropriate for our use case.

We only clear the CacheTree after ensuring that other nodes are blocked out.