apache/dubbo · warning · IllegalStateException

URL Param Cache is full.

Error message

URL Param Cache is full.

What it means

Thrown by DynamicValues.add when the per-key value cache has reached Integer.MAX_VALUE entries. DynamicValues is the dynamic (unbounded-set) ParamValue implementation that intern-distincts URL param values into a growable array indexed by integer. Reaching 2^31-1 distinct values for a single key is a guard against integer overflow, not an expected runtime condition.

Source

Thrown at dubbo-common/src/main/java/org/apache/dubbo/common/url/component/param/DynamicValues.java:44

    public DynamicValues(String defaultVal) {
        if (defaultVal == null) {
            indexSeq += 1;
        } else {
            add(defaultVal);
        }
    }

    public int add(String value) {
        Integer index = value2Index.get(value);
        if (index != null) {
            return index;
        } else {
            synchronized (this) {
                // thread safe
                if (!value2Index.containsKey(value)) {
                    if (indexSeq == Integer.MAX_VALUE) {
                        throw new IllegalStateException("URL Param Cache is full.");
                    }
                    // copy on write, only support append now
                    String[] newValues = new String[indexSeq + 1];
                    System.arraycopy(index2Value, 0, newValues, 0, indexSeq);
                    newValues[indexSeq] = value;
                    index2Value = newValues;
                    value2Index.put(value, indexSeq);
                    indexSeq += 1;
                }
            }
        }
        return value2Index.get(value);
    }

    @Override
    public String getN(int n) {
        if (n == -1) {
            return null;

View on GitHub (pinned to 3a3043227f)

Solutions

1. Treat this as a resource-exhaustion / possible abuse signal: investigate why one param key accumulated billions of distinct values.
2. Restart the JVM to reset the per-framework cache if it is genuinely saturated.
3. Audit where external/untrusted values flow into URL params and bound their cardinality or canonicalize them before intern.

try {
    values.add(v);
} catch (IllegalStateException e) {
    if ("URL Param Cache is full.".equals(e.getMessage())) {
        // effectively unreachable; reset framework cache or restart
    } else throw e;
}

When it happens

Trigger: DynamicValues.add(value) is called after indexSeq has already reached Integer.MAX_VALUE, i.e. more than ~2.1 billion distinct values were interned for one param key. Each new unique value copies the backing array (copy-on-write), so this is effectively unreachable in any realistic deployment.

Common situations: In practice this never fires under normal load. Theoretically it could surface in a pathological long-running process generating enormous cardinality unique param values, or a memory-leak / denial-of-service where an attacker can inject unbounded distinct param values. It signals the internal cache is exhausted.

Related errors

• Cannot found key in url param:{key}
• the array size of values should be larger than 0
• unrecognized value {value} , please check if value is illega
• Failed to release cache path's lock file:{}
• No instance of 'FileCacheStoreFactory' for you!

AI-assisted analysis of apache/dubbo@3a3043227f (2026-08-14). Data as JSON: /api/errors/19003eaaa5928a3b. Report an issue: GitHub.