alibaba/canal · error · NullPointerException

null memoryLogPositionManager

Error message

null memoryLogPositionManager

What it means

PeriodMixedLogPositionManager composes a MemoryLogPositionManager and a ZooKeeperLogPositionManager and periodically flushes the memory copy to ZooKeeper. The memory delegate is mandatory; a null value throws NullPointerException at construction.

Source

Thrown at parse/src/main/java/com/alibaba/otter/canal/parse/index/PeriodMixedLogPositionManager.java:39

public class PeriodMixedLogPositionManager extends AbstractLogPositionManager {

    private static final Logger         logger       = LoggerFactory.getLogger(PeriodMixedLogPositionManager.class);

    private MemoryLogPositionManager    memoryLogPositionManager;
    private ZooKeeperLogPositionManager zooKeeperLogPositionManager;
    private ScheduledExecutorService    executorService;

    private long                        period;
    private Set<String>                 persistTasks;

    @SuppressWarnings("serial")
    private final LogPosition           nullPosition = new LogPosition() {
                                                     };

    public PeriodMixedLogPositionManager(MemoryLogPositionManager memoryLogPositionManager,
                                         ZooKeeperLogPositionManager zooKeeperLogPositionManager, long period){
        if (memoryLogPositionManager == null) {
            throw new NullPointerException("null memoryLogPositionManager");
        }

        if (zooKeeperLogPositionManager == null) {
            throw new NullPointerException("null zooKeeperLogPositionManager");
        }

        if (period <= 0) {
            throw new IllegalArgumentException("period must be positive, given: " + period);
        }

        this.memoryLogPositionManager = memoryLogPositionManager;
        this.zooKeeperLogPositionManager = zooKeeperLogPositionManager;
        this.period = period;
        this.persistTasks = Collections.synchronizedSet(new HashSet<>());
        this.executorService = Executors.newScheduledThreadPool(1);
    }

    @Override

View on GitHub (pinned to 87be50e876)

Solutions

1. Pass a fresh MemoryLogPositionManager as the first argument.
2. Double-check constructor argument order: (memory, zooKeeper, period).
3. Verify the memory manager bean is actually instantiated in the context.

Example fix

// before
new PeriodMixedLogPositionManager(null, zkMgr, period);

// after
new PeriodMixedLogPositionManager(new MemoryLogPositionManager(), zkMgr, period);

MemoryLogPositionManager mem = Objects.requireNonNull(memoryMgr, "memoryLogPositionManager");
new PeriodMixedLogPositionManager(mem, zkMgr, period);

boolean hasMemoryManager(MemoryLogPositionManager m) { return m != null; }

When it happens

Trigger: Constructing PeriodMixedLogPositionManager with memoryLogPositionManager == null. Happens when the in-memory manager bean was not created or was injected as null by the factory.

Common situations: Spring wiring omits the memoryLogPositionManager property; a custom builder returns null; argument order mistake (passing the zk manager into the memory slot).

Related errors

• nul secondary LogPositionManager
• null memoryLogPositionManager
• null metaManager
• null dataDir
• null zkClient

AI-assisted analysis of alibaba/canal@87be50e876 (2026-08-14). Data as JSON: /api/errors/d05de464ede2a5d8. Report an issue: GitHub.