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I opened a heap dump, selected a few items in the Analysis tab, and clicked Perform Analysis. After a couple of minutes, I decided the analysis was taking too long and so I clicked Cancel. But I continued to see heavy disk and CPU activity for a while afterwards. I took a self-sampler and saw: HeapWalker Processor 100.0 17538 ms (100%) 17538 ms 1 org.openide.util.RequestProcessor$Processor.run() 100.0 17538 ms (100%) 17538 ms 1 org.openide.util.RequestProcessor$Task.run() 100.0 17538 ms (100%) 17538 ms 1 org.netbeans.modules.profiler.heapwalk.AnalysisController$1.run() 100.0 17538 ms (100%) 17538 ms 1 org.netbeans.modules.profiler.heapwalk.memorylint.MemoryLint.process() 100.0 17538 ms (100%) 17538 ms 1 org.netbeans.modules.profiler.heapwalk.memorylint.IteratingRule.perform() 100.0 17538 ms (100%) 17538 ms 1 org.netbeans.modules.profiler.heapwalk.memorylint.rules.CollapsedHashMap.summary() 100.0 17538 ms (100%) 17538 ms 1 org.netbeans.modules.profiler.heapwalk.memorylint.rules.CollapsedHashMap$HMRecord.toString() 100.0 17538 ms (100%) 17538 ms 1 org.netbeans.modules.profiler.heapwalk.memorylint.MemoryLint.getRootIncommingString() 100.0 17538 ms (100%) 17538 ms 1 org.netbeans.lib.profiler.heap.InstanceDump.getNearestGCRootPointer() 100.0 17538 ms (100%) 17538 ms 1 org.netbeans.lib.profiler.heap.NearestGCRoot.getNearestGCRootPointer() 100.0 17538 ms (100%) 17538 ms 1 org.netbeans.lib.profiler.heap.NearestGCRoot.computeGCRoots() 100.0 17538 ms (100%) 17538 ms 1 org.netbeans.lib.profiler.heap.NearestGCRoot.computeOneLevel() 99.939354 17528 ms (99.9%) 17528 ms 2 org.netbeans.lib.profiler.heap.NearestGCRoot.writeConnection() 73.8887 12959 ms (73.9%) 12959 ms 397 ....
The main problem is that the computation of references is not cancelable itself. Effectively, the analysis is stuck waiting for the heapwalker engine to finish the computation and can not be canceled.
changing owner
The Analysis view of the HeapWalker is no more being developed (replaced by the OQL Console) and is disabled by default in Profiler options. Won't fix.
Pity, this was the most useful part of the profiler; I hope there is a direct replacement that is as easy to use.