Hi Café, I'm attempting to profile my rather large (~18K LOC) Haskell program that primarily manipulates graph structures based on Data.IntMap. The program is chewing up _lots_ of memory (approx. 4G for 2.5K nodes & 2.5K edges) and I have profiled it in an attempt to figure out why. It appears that the .prof and .hp (which I visualize with hp2ps -c) files do not agree on the source of the problem. The hp results are located at: http://www.eecs.harvard.edu/~uribraun/sybil.ps and the top of the .prof file looks like this: COST CENTRE MODULE %time %alloc compare Policy.Edge 21.7 50.0 eqPartition.edges Policy.EdgeQuad 6.5 3.7 toConstructedSet Types.TaggedIntMultimap 6.1 3.6 elems Types.TaggedIntMap 6.0 6.8 elems Types.TaggedIntSet 5.7 3.8 toPairs Types.TaggedIntMultimap 3.9 5.2 assocs Types.TaggedIntMap 3.2 4.1 eqIsValid Policy.EdgeQuad 2.9 0.5 rIsValid Policy.Relations 2.2 0.2 assocs.\ Types.TaggedIntMap 1.8 0.0 keysSet Types.TaggedIntMap 1.5 1.7 mergeIdenticalNodesT.exactMap Minimize.MergeIdentical 1.4 1.2 fromList Types.TaggedIntSet 1.3 1.6 tePartitionSrc Policy.TaggedEdge 1.2 0.9 null Types.TaggedIntSet 1.2 0.0 scc.comps Policy.Scc 1.2 0.9 tePartitionTgt Policy.TaggedEdge 1.1 0.8 member Types.TaggedIntSet 1.1 0.8 alter Types.TaggedIntMap 1.0 1.1 Also, the line in the .prof that corresponds to the anormUnion.name (what the hprof image claims is taking up space) looks like (some spaces removed): anormUnion.name Anormalize.Anormalize 2914 60 0.0 0.0 0.0 0.0 My main questions at this point are: 1. What are the chances the hprof image is just wrong? 2. What would you suggest I try next in debugging my space issue? This is my first big Haskell program, please do inform me of any big war tools I dont know about. Many thanks in advance! +Uri