alibaba/arthas · error · IllegalArgumentException

Class-pattern is expected, please type the wildcard expressi

Error message

Class-pattern is expected, please type the wildcard expression to match

What it means

Thrown by checkArguments() in the `tt` command when the record mode (-t) is active but no class-pattern is provided. Time-tunnel recording must match a class via a wildcard expression, so a non-empty class-pattern is mandatory.

Source

Thrown at core/src/main/java/com/taobao/arthas/core/command/monitor200/TimeTunnelCommand.java:261

    /**
     * 检查参数是否合法
     */
    private void checkArguments() {
        String validateError = validateSizeLimit(sizeLimit);
        if (validateError != null) {
            throw new IllegalArgumentException(validateError);
        }

        // 检查d/p参数是否有i参数配套
        if ((isDelete || isPlay) && null == index) {
            throw new IllegalArgumentException("Time fragment index is expected, please type -i to specify");
        }

        // 在t参数下class-pattern,method-pattern
        if (isTimeTunnel) {
            if (StringUtils.isEmpty(classPattern)) {
                throw new IllegalArgumentException("Class-pattern is expected, please type the wildcard expression to match");
            }
            if (StringUtils.isEmpty(methodPattern)) {
                throw new IllegalArgumentException("Method-pattern is expected, please type the wildcard expression to match");
            }
        }

        // 一个参数都没有是不行滴
        if (null == index && !isTimeTunnel && !isDeleteAll && StringUtils.isEmpty(watchExpress)
                && !isList && StringUtils.isEmpty(searchExpress)) {
            throw new IllegalArgumentException("Argument(s) is/are expected, type 'help tt' to read usage");
        }
    }

    /*
     * 记录时间片段
     */
    int putTimeTunnel(TimeFragment tt) {
        int indexOfSeq = sequence.getAndIncrement();

View on GitHub (pinned to 21cf2e9ba5)

Solutions

1. Add `--class-pattern <wildcard>` (e.g. the FQN or a wildcard like demo.MathGame).
2. Use `tt --help` to confirm the required options for record mode.

Example fix

// before
tt -t --method-pattern primeFactors
// after
tt -t --class-pattern demo.MathGame --method-pattern primeFactors

if (isTimeTunnel && (classPattern == null || classPattern.trim().isEmpty())) {
    fail("-t requires --class-pattern");
}

null

null

When it happens

Trigger: Running `tt -t` without `--class-pattern`, e.g. `tt -t --method-pattern prime` with the class missing.

Common situations: Forgetting the class-pattern; assuming -t takes positional args; passing an empty --class-pattern "".

Related errors

• Method-pattern is expected, please type the wildcard express
• Time fragment index is expected, please type -i to specify
• Argument(s) is/are expected, type 'help tt' to read usage
• sizeLimit must be greater than 0.
• 必须提供 path 或 cursor

AI-assisted analysis of alibaba/arthas@21cf2e9ba5 (2026-08-14). Data as JSON: /api/errors/744d27133881eff3. Report an issue: GitHub.