alibaba/Sentinel · error · IllegalArgumentException

bufSize must between (0, ${MAX_SIZE}], but ${bufSize} get

Error message

bufSize must between (0, ${MAX_SIZE}], but ${bufSize} get

What it means

FileRefreshableDataSource reads a whole config file into a fixed byte buffer (bufSize) on each refresh. Its constructor validates 0 < bufSize <= MAX_SIZE and throws IllegalArgumentException otherwise — same policy as FileInJarReadableDataSource, applied before the file/charset checks.

Source

Thrown at sentinel-extension/sentinel-datasource-extension/src/main/java/com/alibaba/csp/sentinel/datasource/FileRefreshableDataSource.java:81

    public FileRefreshableDataSource(String fileName, Converter<String, T> configParser) throws FileNotFoundException {
        this(new File(fileName), configParser, DEFAULT_REFRESH_MS, DEFAULT_BUF_SIZE, DEFAULT_CHAR_SET);
    }

    public FileRefreshableDataSource(File file, Converter<String, T> configParser, int bufSize)
        throws FileNotFoundException {
        this(file, configParser, DEFAULT_REFRESH_MS, bufSize, DEFAULT_CHAR_SET);
    }

    public FileRefreshableDataSource(File file, Converter<String, T> configParser, Charset charset)
        throws FileNotFoundException {
        this(file, configParser, DEFAULT_REFRESH_MS, DEFAULT_BUF_SIZE, charset);
    }

    public FileRefreshableDataSource(File file, Converter<String, T> configParser, long recommendRefreshMs, int bufSize,
                                     Charset charset) throws FileNotFoundException {
        super(configParser, recommendRefreshMs);
        if (bufSize <= 0 || bufSize > MAX_SIZE) {
            throw new IllegalArgumentException("bufSize must between (0, " + MAX_SIZE + "], but " + bufSize + " get");
        }
        if (file == null || file.isDirectory()) {
            throw new IllegalArgumentException("File can't be null or a directory");
        }
        if (charset == null) {
            throw new IllegalArgumentException("charset can't be null");
        }
        this.buf = new byte[bufSize];
        this.file = file;
        this.charset = charset;
        // If the file does not exist, the last modified will be 0.
        this.lastModified = file.lastModified();
        firstLoad();
    }

    private void firstLoad() {
        try {
            T newValue = loadConfig();

View on GitHub (pinned to a3f40ba8e9)

Solutions

1. Pass a bufSize in (0, MAX_SIZE]; if unsure, omit it and rely on DEFAULT_BUF_SIZE.
2. Audit the expression producing bufSize — ensure it cannot be 0 or negative before the constructor call.
3. Remember this datasource reads the file in one shot: bufSize must cover the full config file or later reads will fail a size check like the jar variant.

Example fix

// before
new FileRefreshableDataSource<>(file, parser, 3000, Integer.parseInt(props.getProperty("buf", "0")), charset);

// after
int bufSize = Integer.parseInt(props.getProperty("buf", String.valueOf(FileRefreshableDataSource.DEFAULT_BUF_SIZE)));
new FileRefreshableDataSource<>(file, parser, 3000, bufSize, charset);

int bufSize = props.getProperty("bufSize") == null
    ? FileRefreshableDataSource.DEFAULT_BUF_SIZE
    : Integer.parseInt(props.getProperty("bufSize"));
if (bufSize <= 0 || bufSize > FileRefreshableDataSource.DEFAULT_BUF_SIZE /* MAX_SIZE */) {
    throw new ConfigurationException("bufSize out of range: " + bufSize);
}
new FileRefreshableDataSource<>(file, parser, refreshMs, bufSize, charset);

boolean isValidBufSize(int bufSize) {
    return bufSize > 0 && bufSize <= FileRefreshableDataSource.DEFAULT_BUF_SIZE;
}

When it happens

Trigger: new FileRefreshableDataSource(file, parser, recommendRefreshMs, bufSize, charset) with bufSize <= 0 or bufSize > MAX_SIZE; also reachable via the 5-arg overload from the 4-arg convenience constructor only if you pass an explicit bad size (defaults are safe).

Common situations: bufSize derived from a runtime computation (e.g. file length check order) or a config property defaulting to 0; migrating from a version where the argument order/semantics of the varargs constructor changed.

Related errors

• bufSize must between (0, ${MAX_SIZE}], but ${bufSize} get
• recommendRefreshMs must > 0, but {} get
• File can't be null or a directory
• Bad file
• keys empty or null: ${keys}

AI-assisted analysis of alibaba/Sentinel@a3f40ba8e9 (2026-08-14). Data as JSON: /api/errors/deb30f71b9f30792. Report an issue: GitHub.