{"record":{"id":"71928cd4e320c672","repo":"alibaba/spring-ai-alibaba","slug":"failed-to-add-next-node-to-queue","errorCode":null,"errorMessage":"Failed to add next node to queue: ","messagePattern":"Failed to add next node to queue: ","errorType":"exception","errorClass":"IllegalStateException","httpStatus":null,"severity":"error","filePath":"spring-ai-alibaba-graph-core/src/main/java/com/alibaba/cloud/ai/graph/internal/ParallelEdgeProcessor.java","lineNumber":359,"sourceCode":"\t\t\t}\n\n\t\t\tString nextNode = target.id();\n\n\t\t\t// Update reachability: all sources that reached current also reach nextNode\n\t\t\tSet<String> nextSources = reachableFrom.computeIfAbsent(nextNode, k -> new HashSet<>());\n\t\t\tint sizeBefore = nextSources.size();\n\t\t\tnextSources.addAll(sources);\n\t\t\tboolean sourcesChanged = nextSources.size() > sizeBefore;\n\n\t\t\t// If this node is reachable from all start nodes, it's the convergence point\n\t\t\tif (nextSources.size() == startNodeIds.size()) {\n\t\t\t\treturn nextNode;\n\t\t\t}\n\n\t\t\t// Only queue if sources actually changed (prevents infinite loops in cycles)\n\t\t\tif (sourcesChanged && nextSources.size() < startNodeIds.size()) {\n\t\t\t\tif (!queue.offer(nextNode)) {\n\t\t\t\t\tthrow new IllegalStateException(\"Failed to add next node to queue: \" + nextNode);\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\n\t\treturn null;\n\t}\n\n\t/**\n\t * Finds the end of a path starting from the given node.\n\t * Follows edges until reaching a node with no outgoing edges or END.\n\t */\n\tprivate String findPathEnd(String startNode) {\n\t\tString current = startNode;\n\t\tSet<String> visited = new HashSet<>();\n\n\t\twhile (current != null && !visited.contains(current)) {\n\t\t\tvisited.add(current);\n\t\t\tOptional<Edge> edgeOpt = processedData.edges().edgeBySourceId(current);","sourceCodeStart":341,"sourceCodeEnd":377,"githubUrl":"https://github.com/alibaba/spring-ai-alibaba/blob/f82da0b50f35744c13968191be2b1cd2452ef550/spring-ai-alibaba-graph-core/src/main/java/com/alibaba/cloud/ai/graph/internal/ParallelEdgeProcessor.java#L341-L377","documentation":"In the same fixpoint traversal, the successor of the current node is re-queued when its reachable-source set changed and it is not yet a full convergence point. A failed queue.offer raises this IllegalStateException — again a defensive check that should never trigger with an unbounded ArrayDeque.","triggerScenarios":"queue.offer(nextNode) returns false while queueing a successor node during convergence detection — practically impossible for an unbounded ArrayDeque.","commonSituations":"Not reachable in normal use; signals corrupted or modified library internals.","solutions":["Verify the official, unmodified release of spring-ai-alibaba-graph-core is in use.","Report the issue with the graph topology if reproducible.","Rebuild the dependency to rule out artifact corruption."],"exampleFix":null,"handlingStrategy":"retry","validationCode":null,"typeGuard":null,"tryCatchPattern":"try { graph.compile(); } catch (IllegalStateException e) { if (e.getMessage().startsWith(\"Failed to add next node to queue\")) { /* rebuild dependency / report bug */ } }","preventionTips":["Use official release artifacts only","Pin dependency versions","Rebuild the module from source if customized"],"tags":["internal","queue","convergence-analysis","defensive-check"],"backgroundTag":"internal-invariant-violation","analyzedSha":"f82da0b50f35744c13968191be2b1cd2452ef550","analyzedAt":"2026-09-09T15:32:42.421Z","contentChangedAt":"2026-09-09T15:32:42.421Z","schemaVersion":2},"datasetVersion":"2026-09-17T15:17:12.973Z"}