apache/cassandra · error · RuntimeException

KeyCacheSavePeriodInSeconds must be non-negative.

Error message

KeyCacheSavePeriodInSeconds must be non-negative.

What it means

CacheService.setKeyCacheSavePeriodInSeconds validates that the key-cache autosave interval is not negative before storing it and rescheduling the key cache saver. A negative value has no meaning as a periodic save interval, so the setter rejects it eagerly with an untyped RuntimeException. This setter is typically invoked via JMX at runtime rather than from application code.

Solutions

1. Pass a non-negative value: clamp with Math.max(0, seconds) before calling the setter.
2. Use 0 to disable periodic key cache saving instead of a negative number.
3. Check the source of the value (config parsing, unit conversion) for sign errors.
4. If the intent is a disabled interval, also consider removing the runtime update entirely so the cassandra.yaml value is kept.

Example fix

// before
cacheService.setKeyCacheSavePeriodInSeconds(getInterval());
// after
int seconds = getInterval();
if (seconds >= 0)
    cacheService.setKeyCacheSavePeriodInSeconds(seconds);

if (seconds < 0) throw new IllegalArgumentException("KeyCacheSavePeriodInSeconds must be >= 0");
cacheService.setKeyCacheSavePeriodInSeconds(seconds);

When it happens

Trigger: Calling CacheService.setKeyCacheSavePeriodInSeconds(seconds) with seconds < 0, e.g. via JMX (org.apache.cassandra.service.CacheService mbean) or internal code passing a negative duration value.

Common situations: Operators pushing a runtime JMX config change computed from a bad expression (e.g. unit conversion yielding a negative number), scripts that subtract timestamps, or hand-editing JMX console fields with a minus sign.

Related errors

• CounterCacheKeysToSave must be non-negative.
• CounterCacheSavePeriodInSeconds must be non-negative.
• KeyCacheKeysToSave must be non-negative.
• RowCacheKeysToSave must be non-negative.
• capacity should not be negative.

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/2f779902bb8f4c7c. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/service/CacheService.java:217

    public void setRowCacheSavePeriodInSeconds(int seconds)
    {
        if (seconds < 0)
            throw new RuntimeException("RowCacheSavePeriodInSeconds must be non-negative.");

        DatabaseDescriptor.setRowCacheSavePeriod(seconds);
        rowCache.scheduleSaving(seconds, DatabaseDescriptor.getRowCacheKeysToSave());
    }

    public int getKeyCacheSavePeriodInSeconds()
    {
        return DatabaseDescriptor.getKeyCacheSavePeriod();
    }

    public void setKeyCacheSavePeriodInSeconds(int seconds)
    {
        if (seconds < 0)
            throw new RuntimeException("KeyCacheSavePeriodInSeconds must be non-negative.");

        DatabaseDescriptor.setKeyCacheSavePeriod(seconds);
        keyCache.scheduleSaving(seconds, DatabaseDescriptor.getKeyCacheKeysToSave());
    }

    public int getCounterCacheSavePeriodInSeconds()
    {
        return DatabaseDescriptor.getCounterCacheSavePeriod();
    }

    public void setCounterCacheSavePeriodInSeconds(int seconds)
    {
        if (seconds < 0)
            throw new RuntimeException("CounterCacheSavePeriodInSeconds must be non-negative.");

        DatabaseDescriptor.setCounterCacheSavePeriod(seconds);
        counterCache.scheduleSaving(seconds, DatabaseDescriptor.getCounterCacheKeysToSave());
    }

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