alibaba/Sentinel · error · IllegalStateException

arraySet() is unavailable if countAndSum() has been called

Error message

arraySet() is unavailable if countAndSum() has been called

What it means

StatEntryFuncCountAndSum implements the count-and-sum strategy (an AtomicLong count plus an AtomicLong sum). arraySet(long... values) belongs to the array-slot strategy where each slot is assigned a value; calling it on a count-and-sum entry throws IllegalStateException because the entry's internal state (two scalars) cannot represent an array of slots.

Source

Thrown at sentinel-core/src/main/java/com/alibaba/csp/sentinel/eagleeye/StatEntryFunc.java:99

    @Override
    public void count(long count) {
        this.count.add(count);
    }

    @Override
    public void countAndSum(long count, long value) {
        this.count.add(count);
        this.value.add(value);
    }

    @Override
    public void arrayAdd(long... values) {
        throw new IllegalStateException("arrayAdd() is unavailable if countAndSum() has been called");
    }

    @Override
    public void arraySet(long... values) {
        throw new IllegalStateException("arraySet() is unavailable if countAndSum() has been called");
    }

    @Override
    public void minMax(long candidate, String ref) {
        throw new IllegalStateException("minMax() is unavailable if countAndSum() has been called");
    }

    @Override
    public void batchAdd(long... values) {
        throw new IllegalStateException("batchAdd() is unavailable if countAndSum() has been called");
    }

    @Override
    public void strArray(String... values) {
        throw new IllegalStateException("strArray() is unavailable if countAndSum() has been called");
    }
}

View on GitHub (pinned to a3f40ba8e9)

Solutions

Change the write call to countAndSum(count, value) (or count(count)) to match the entry type.
Or change the entry creation to the array type if slot assignment is what you need.
Add a unit test per metric name asserting the writer matches the configured stat type.

Example fix

// before
entryFunc.arraySet(dailyTotals); // entry is count-and-sum -> throws

// after
entryFunc.countAndSum(1, delta);

Defensive patterns

Strategy: type-guard

Validate before calling

if (func.getStatType() == 2) { func.countAndSum(1, value); } else { func.arraySet(values); }

Type guard

boolean isCountAndSum(StatEntryFunc f) { return f.getStatType() == 2; }

Prevention

Keep metric type and writer method adjacent in code/config so they change together.
Avoid generic write-all recorders; use per-strategy recorder classes.
Add a compile-time-ish check: assert strategy support in a unit test per metric.

When it happens

Trigger: Calling arraySet(values) on an entry whose func is StatEntryFuncCountAndSum — typically a reporting loop that was written for an arraySet-style metric but is applied to a countAndSum entry, or a config-driven metric definition whose type and writer disagree.

Common situations: Metric definitions live in configuration; the type says count_and_sum but the emitter code calls arraySet. Code reuse across metric modules with different entry types. Migration from array metrics to count/sum metrics where one call site was missed.

Related errors

AI-assisted analysis of alibaba/Sentinel@a3f40ba8e9 (2026-08-14). Data as JSON: /api/errors/f5ea0ec2ea091ab4. Report an issue: GitHub.