redis/jedis · error · IllegalArgumentException

Buffer size <= 0

Error message

Buffer size <= 0

What it means

RedisInputStream wraps an InputStream with an internal buffer for the RESP protocol parser. The constructor validates that the requested buffer size is positive and throws IllegalArgumentException("Buffer size <= 0") otherwise, because a zero/negative buffer cannot hold any bytes.

Solutions

1. Pass a positive size (use the no-arg constructor RedisInputStream(in) to get the default INPUT_BUFFER_SIZE).
2. Clamp/validate your configured size before construction: Math.max(minBufferSize, configuredSize).
3. If the size is computed, check the computation for overflow or zero-division results.

Example fix

// before
int size = config.getBufferSize(); // 0 when unset
RedisInputStream in = new RedisInputStream(raw, size); // throws
// after
int size = Math.max(1024, config.getBufferSize());
RedisInputStream in = new RedisInputStream(raw, size);

static RedisInputStream safeWrap(InputStream in, int size) {
  if (size <= 0) size = 8192; // or use RedisInputStream(in) default
  return new RedisInputStream(in, size);
}

try {
  stream = new RedisInputStream(in, size);
} catch (IllegalArgumentException e) {
  stream = new RedisInputStream(in); // default buffer
}

When it happens

Trigger: Constructing `new RedisInputStream(in, 0)` or with a negative size — e.g. a size computed from a config value, constant folding error, or an int overflow.

Common situations: Buffer size read from configuration where the value is 0/unset and cast to int without validation; misconfigured custom protocol clients.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• Unknown protocol
• protocol must not be null
• Unknown message type
• Unknown message type:
• Unknown reply:

AI-assisted analysis of redis/jedis@6dac31d4c2 (2026-09-08). Data as JSON: /api/errors/4ffb3325f075305a. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/redis/clients/jedis/util/RedisInputStream.java:39

/**
 * This class assumes (to some degree) that we are reading a RESP stream. As such it assumes certain
 * conventions regarding CRLF line termination. It also assumes that if the Protocol layer requires
 * a byte that if that byte is not there it is a stream error.
 */
public class RedisInputStream extends FilterInputStream {

  private static final int INPUT_BUFFER_SIZE = Integer.parseInt(
      System.getProperty("jedis.bufferSize.input",
          System.getProperty("jedis.bufferSize", "8192")));

  protected final byte[] buf;

  protected int count, limit;

  public RedisInputStream(InputStream in, int size) {
    super(in);
    if (size <= 0) {
      throw new IllegalArgumentException("Buffer size <= 0");
    }
    buf = new byte[size];
  }

  public RedisInputStream(InputStream in) {
    this(in, INPUT_BUFFER_SIZE);
  }

  @Experimental
  public boolean peek(byte b) throws JedisConnectionException {
    ensureFill(); // in current design, at least one reply is expected. so ensureFillSafe() is not necessary.
    return buf[count] == b;
  }

  public byte readByte() throws JedisConnectionException {
    ensureFill();
    return buf[count++];
  }

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