apache/skywalking · error · IllegalArgumentException

buckets and values can't be null.

Error message

buckets and values can't be null.

What it means

BucketedValues is the value object histogram meter functions accept; its constructor requires a non-null, non-empty buckets array and a non-null, non-empty values array. Violating any of the four conditions (either array null or zero-length) throws this IllegalArgumentException before any aggregation happens, protecting downstream index arithmetic that assumes buckets.length > 0.

Source

Thrown at oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/meter/function/BucketedValues.java:59

     * The element in the buckets represent the minimal value of this bucket, the max is defined by the next element.
     * Such as 0, 10, 50, 100 means buckets are [0, 10), [10, 50), [50, 100), [100, infinite+).
     *
     * The {@link Long#MIN_VALUE} could be the first bucket element to indicate there is no minimal value.
     */
    private long[] buckets;
    /**
     * {@link #buckets} and {@link #values} arrays should have the same length. The element in the values, represents
     * the amount in the same index bucket.
     */
    private long[] values;

    /**
     * @param buckets Read {@link #buckets}
     * @param values  Read {@link #values}
     */
    public BucketedValues(final long[] buckets, final long[] values) {
        if (buckets == null || values == null || buckets.length == 0 || values.length == 0) {
            throw new IllegalArgumentException("buckets and values can't be null.");
        }
        if (buckets.length != values.length) {
            throw new IllegalArgumentException("The length of buckets and values should be same.");
        }
        this.buckets = buckets;
        this.values = values;
    }

    /**
     * @return true if the bucket is same.
     */
    public boolean isCompatible(DataTable dataset) {
        final List<String> sortedKeys = dataset.sortedKeys(new HeatMap.KeyComparator(true));
        long[] existedBuckets = new long[sortedKeys.size()];
        for (int i = 0; i < sortedKeys.size(); i++) {
            String key = sortedKeys.get(i);
            if (key.equals(Bucket.INFINITE_NEGATIVE)) {
                existedBuckets[i] = Long.MIN_VALUE;

View on GitHub (pinned to 102af09b4a)

Solutions

1. Skip emitting the histogram metric for this cycle when buckets or values would be empty instead of constructing BucketedValues
2. Fix the producer so it always sends a well-formed bucket set (bucket boundaries plus one value per bucket)
3. Validate telemetry at the receiving boundary and reject/log malformed empty histograms before they reach accept()

Example fix

// before
long[] buckets = fetchBuckets(); // may be empty
new BucketedValues(buckets, values);

// after
long[] buckets = fetchBuckets();
if (buckets != null && buckets.length > 0 && values != null && values.length == buckets.length) {
    new BucketedValues(buckets, values);
} else {
    log.debug("Skip empty histogram for {}", metricName);
}

if (buckets == null || values == null || buckets.length == 0 || values.length == 0) {
    log.debug("Skipping empty histogram for {}", metricName);
} else {
    BucketedValues bv = new BucketedValues(buckets, values);
    histogram.accept(entity, bv);
}

boolean isWellFormedHistogram(long[] buckets, long[] values) {
    return buckets != null && values != null
        && buckets.length > 0 && values.length == buckets.length;
}

When it happens

Trigger: A MAL rule or agent SDK builds BucketedValues from empty or null telemetry — e.g. a bucketed expression produced no points this cycle, or upstream code passes uninitialized arrays; a custom meter sender serializes an empty histogram.

Common situations: Meter/OTel receivers forwarding empty histogram batches; agent plugins computing buckets conditionally and passing null when the condition fails; test fixtures with empty arrays.

Related errors

• The length of buckets and values should be same.
• Incompatible BucketedValues [{}] for current HistogramFuncti
• Illegal rank value {rank}, must be positive
• decorate() not supported for histogram metrics
• YAML parsed to null — empty or malformed rule file: {sourceN

AI-assisted analysis of apache/skywalking@102af09b4a (2026-08-14). Data as JSON: /api/errors/ef6d8d9a83a4eebf. Report an issue: GitHub.