eclipse-vertx/vert.x · error · IllegalArgumentException

There is no larger power of 2 int for value:${value} since i

Error message

There is no larger power of 2 int for value:${value} since it exceeds 2^31.

What it means

HybridJacksonPool's roundToPowerOfTwo rounds a pool size up to the next power of two, capped at 2^30 (MAX_POW2). Values above the cap cannot be represented as a power-of-two int, so the helper throws IllegalArgumentException stating no larger power of 2 exists below 2^31.

Source

Thrown at vertx-core/src/main/java/io/vertx/core/json/jackson/HybridJacksonPool.java:203

    private int probe() {
      // Multiplicative Fibonacci hashing implementation
      // 0x9e3779b9 is the integral part of the Golden Ratio's fractional part 0.61803398875… (sqrt(5)-1)/2
      // multiplied by 2^32, which has the best possible scattering properties.
      int probe = (int) ((Thread.currentThread().getId() * 0x9e3779b9) & Integer.MAX_VALUE);
      // xorshift
      probe ^= probe << 13;
      probe ^= probe >>> 17;
      probe ^= probe << 5;
      return probe;
    }
  }

  private static final int MAX_POW2 = 1 << 30;

  private static int roundToPowerOfTwo(final int value) {
    if (value > MAX_POW2) {
      throw new IllegalArgumentException(
        "There is no larger power of 2 int for value:" + value + " since it exceeds 2^31.");
    }
    if (value < 0) {
      throw new IllegalArgumentException("Given value:" + value + ". Expecting value >= 0.");
    }
    final int nextPow2 = 1 << (32 - Integer.numberOfLeadingZeros(value - 1));
    return nextPow2;
  }
}

View on GitHub (pinned to fb308bd8c3)

Solutions

1. Cap the pool size at 1 << 30 before construction: Math.min(value, 1 << 30)
2. Correct the misconfigured size property to a sane value (e.g. CPU count)
3. Validate user/config-supplied sizes against the 2^30 limit before passing them to the pool

Example fix

// before
int stripes = Integer.getInteger("pool.stripes", 16) * 1_000_000; // exceeds 2^30
new StripedLockFreePool(stripes);
// after
int stripes = Math.min(1 << 30, Math.max(1, Integer.getInteger("pool.stripes", 16)));
new StripedLockFreePool(stripes);

if (value > (1 << 30)) throw new IllegalArgumentException("pool size must be <= 2^30");

try {
  pool = new HybridJacksonPool.StripedLockFreePool(rawSize);
} catch (IllegalArgumentException e) {
  pool = new HybridJacksonPool.StripedLockFreePool(1024);
}

When it happens

Trigger: Constructing StripedLockFreePool with stripesCount > 2^30 (1,073,741,824), which roundToPowerOfTwo then rejects — usually from an absurdly large configured pool size.

Common situations: Typo in a size system property (e.g. passing bytes instead of count); misconfigured property like 107374182400; unbounded computation like Integer.MAX_VALUE used as pool size.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• Expecting a stripesCount that is larger than 0
• Given value:${value}. Expecting value >= 0.
• Expecting a stripesCount that is larger than 0
• workerPoolSize must be > 0
• Can't register a system codec

AI-assisted analysis of eclipse-vertx/vert.x@fb308bd8c3 (2026-09-06). Data as JSON: /api/errors/54105fd7621da3b7. Report an issue: GitHub.