{"record":{"id":"ca69d8bec7788aed","repo":"nathanmarz/storm","slug":"spout-has-already-been-declared-for-id-id","errorCode":null,"errorMessage":"Spout has already been declared for id ${id}","messagePattern":"Spout has already been declared for id (.+?)","errorType":"exception","errorClass":"IllegalArgumentException","httpStatus":null,"severity":"error","filePath":"storm-core/src/jvm/backtype/storm/topology/TopologyBuilder.java","lineNumber":215,"sourceCode":"        return new SpoutGetter(id);\n    }\n\n    public void setStateSpout(String id, IRichStateSpout stateSpout) {\n        setStateSpout(id, stateSpout, null);\n    }\n\n    public void setStateSpout(String id, IRichStateSpout stateSpout, Number parallelism_hint) {\n        validateUnusedId(id);\n        // TODO: finish\n    }\n\n\n    private void validateUnusedId(String id) {\n        if(_bolts.containsKey(id)) {\n            throw new IllegalArgumentException(\"Bolt has already been declared for id \" + id);\n        }\n        if(_spouts.containsKey(id)) {\n            throw new IllegalArgumentException(\"Spout has already been declared for id \" + id);\n        }\n        if(_stateSpouts.containsKey(id)) {\n            throw new IllegalArgumentException(\"State spout has already been declared for id \" + id);\n        }\n    }\n\n    private ComponentCommon getComponentCommon(String id, IComponent component) {\n        ComponentCommon ret = new ComponentCommon(_commons.get(id));\n        \n        OutputFieldsGetter getter = new OutputFieldsGetter();\n        component.declareOutputFields(getter);\n        ret.set_streams(getter.getFieldsDeclaration());\n        return ret;        \n    }\n    \n    private void initCommon(String id, IComponent component, Number parallelism) {\n        ComponentCommon common = new ComponentCommon();\n        common.set_inputs(new HashMap<GlobalStreamId, Grouping>());","sourceCodeStart":197,"sourceCodeEnd":233,"githubUrl":"https://github.com/nathanmarz/storm/blob/cdb116e942666973bc4eaa0df098d5bab82739e7/storm-core/src/jvm/backtype/storm/topology/TopologyBuilder.java#L197-L233","documentation":"TopologyBuilder.validateUnusedId throws IllegalArgumentException when setSpout (or setBolt/setStateSpout) is called with an id that is already registered as a spout. Component ids must be globally unique in a Storm topology.","triggerScenarios":"Calling builder.setSpout(id, ...) with an id previously used for a spout; loops re-adding spouts with the same id; reusing a builder that already has the id registered.","commonSituations":"Multiple data sources declared with the same constant id like \"spout\"; copy-paste of a spout declaration where the id was not updated; programmatic topology generation with an off-by-one id counter.","solutions":["Rename the spout so its id is unique across bolts, spouts, and state spouts","Use unique generated ids (e.g. \"spout-\" + name) when declaring multiple spouts","Create a new TopologyBuilder instead of reusing a populated one","Grep for duplicate setSpout calls with identical id strings"],"exampleFix":"// before\nbuilder.setSpout(\"src\", new KafkaSpout());\nbuilder.setSpout(\"src\", new TwitterSpout()); // throws\n// after\nbuilder.setSpout(\"kafka\", new KafkaSpout());\nbuilder.setSpout(\"twitter\", new TwitterSpout());","handlingStrategy":"validation","validationCode":"Set<String> used = new HashSet<>();\nvoid safeSpout(TopologyBuilder b, String id, IRichSpout spout) {\n    if (!used.add(id))\n        throw new IllegalStateException(\"duplicate component id: \" + id);\n    b.setSpout(id, spout);\n}","typeGuard":null,"tryCatchPattern":"try {\n    builder.setSpout(id, spout);\n} catch (IllegalArgumentException e) {\n    if (!e.getMessage().contains(\"already been declared\")) throw e;\n    // handle duplicate id\n}","preventionTips":["Use a single id registry/counter for all components (spouts, bolts, state spouts)","Never reuse a populated TopologyBuilder","Review copy-pasted spout declarations for stale ids"],"tags":["topology","duplicate-id","storm"],"backgroundTag":"invalid-argument-value","analyzedSha":"cdb116e942666973bc4eaa0df098d5bab82739e7","analyzedAt":"2026-09-12T14:30:00.714Z","contentChangedAt":"2026-09-12T14:30:00.714Z","schemaVersion":2},"datasetVersion":"2026-09-16T09:17:16.951Z"}