As for me, there's no reason to store IGFS blocks in cache with on-heap
layer enabled.
I vote for the first option: deprecate/remove
IgfsPerBlockLruEvictionPolicy (along with tests), recommend users to use
page-based eviction if they need to evict blocks from primary IGFS.
--
Best Regards,
Ivan Rakov
On 24.05.2017 19:57, Ivan V. wrote:
Hi, colleagues,
as Ignite caches moved to paged offheap memory , the
IgfsPerBlockLruEvictionPolicy does not seem to work as expected any more,
because
1) interface org.apache.ignite.cache.eviction.EvictionPolicy now only
defines "eviction from on-heap", not a real eviction, because each on-heap
cache is now accompanied with underlying off-heap cache. It can become
"real eviction" only for "on-heap-only" mode caches, once they get
implemented.
2) for off-heap eviction an entire page is evicted, not a specific k-v
pair, and LRU policy is not exactly LRU any more (see
org.apache.ignite.configuration.DataPageEvictionMode#RANDOM_LRU). So, it
appears to be impossible to re-implement this policy for the off-heap layer.
Thus, now IgfsPerBlockLruEvictionPolicy is not quite valid, and some of
corresponding tests fail
(org.apache.ignite.internal.processors.igfs.IgfsCachePerBlockLruEvictionPolicySelfTest#testDataSizeEviction,
org.apache.ignite.internal.processors.igfs.IgfsCachePerBlockLruEvictionPolicySelfTest#testBlockCountEviction)
So, the options I see are:
1) deprecate/remove IgfsPerBlockLruEvictionPolicy ;
2) leave it as is, but explain in javadocs that it only works for on-heap
layer, that does not in fact evict blocks from the underlying offheap
layer.
Please share your opinions.
