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java-topology/docs/tickets/storm-0002-workerstate-localtaskids-arraylist-contains.md
russell@unturf.com 9934133dcf whitepaper: 312 sites / 151 ecosystems — wave2+3 defect tables and PDF rebuild 
Add 88 new defect entries to HIGH and MEDIUM tables:
  HIGH: mysql-0001/0002, mariadb-0001, redis-0001/0002, valkey-0001/0002, openvpn-0001,
        vlc-0001, prometheus-0001, otel-collector-0001, cockroachdb-0001..0004,
        tidb-0001..0008, kubernetes-0001/0002, go-0001, kotlin-0002, scala-0001,
        allegro5-0001, sdl2-0001, grafana-0001, clickhouse-0001, duckdb-0001,
        mongodb-0001, envoy-0001, istio-0001, cilium-0001, linkerd2-0001,
        linux-0001/0002/0003, tor-0002/0003, curl-0001, julia-0001, lua-0001,
        perl5-0001, nats-0001, spring-0003/0004, tomcat-0001, onos-0002, odl-0002

  MEDIUM: helm-0001, mariadb-0002, openssl-0001/0002, memcached-0001,
          cassandra-0001..0004, flink-0001, storm-0001/0002, zookeeper-0001..0003,
          pip-0001, gradle-0001, nginx-0001, haproxy-0001, caddy-0001, varnish-0001,
          ffmpeg-0001, gstreamer-0001, raylib-0001, love2d-0001, php-0001/0002,
          r-source-0001, cpython-0002, ruby-0001, rabbitmq-0003/0004, activemq-0001,
          ovs-0001, onos-0003, odl-0002, jetty-0001

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2026-03-27 15:23:43 -04:00

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storm-0002: WorkerState topology reassignment — ArrayList.contains() O(n²)

Target: Apache Storm File: storm-client/src/jvm/org/apache/storm/daemon/worker/WorkerState.java CWE: CWE-407 — Inefficient Algorithmic Complexity Severity: MEDIUM Status: PATCHED

Description

WorkerState.refreshConnections() iterates over all tasks in the assignment (outer loop, O(n)) and calls localTaskIds.contains(task) where localTaskIds is an ArrayList<Integer> (inner O(n) scan), yielding O(n²) per reassignment event.

// storm-client/.../worker/WorkerState.java  line 112 / 424-431
final ArrayList<Integer> localTaskIds;          // O(n) contains

// in refreshConnections():
for (Map.Entry<Integer, NodeInfo> taskToNodePortEntry : taskToNodePort.entrySet()) {
    Integer task = taskToNodePortEntry.getKey();
    if (outboundTasks.contains(task)) {          // outboundTasks is Set<Integer> — O(1)
        newTaskToNodePort.put(task, taskToNodePortEntry.getValue());
        if (!localTaskIds.contains(task)) {      // ArrayList — O(n) ← defect
            neededConnections.add(taskToNodePortEntry.getValue());
        }
    }
}

outboundTasks is already a Set<Integer> so that check is O(1). localTaskIds should also be a HashSet<Integer> for the membership check.

Fix

Maintain a parallel Set<Integer> localTaskIdSet (or convert localTaskIds to LinkedHashSet) so that localTaskIds.contains() becomes O(1).

Patch

defects/storm/patch/storm-0002.patch

Unit Test

defects/storm/unit/StormWorkerStateTaskLookupTest.java