Possible memory leak in `LookUpTableGrid.CACHE`

[grojeda]

We are investigating recurring OOMs in a production TDS 5.9 deployment using EDAL 1.5.3.3.

A heap dump analysed with Eclipse MAT showed that:

• LookUpTableGrid.CACHE retained ~4.56 GB (~90%) of the analysed heap
• the cache contained 390 CurvilinearCoords -> LookUpTableGrid entries
• the GC root path confirmed the static CACHE was keeping these objects alive

The cache is currently an unbounded static HashMap with no size limit, TTL or eviction policy.

A later JVM also showed 620 live instances of each of:

CurvilinearCoords
LookUpTableGrid
LookUpTable

This looks consistent with curvilinear grids accumulating over the JVM lifetime.

Would it make sense to make this cache bounded or add an eviction/expiry policy?

Related TDS issue: Unidata/tds#689
Possibly related: Unidata/tds#684