sebastianbergmann/php-timer · error · TimeSinceStartOfRequestNotAvailableException

Cannot determine time at which the request started because…

Error message

Cannot determine time at which the request started because $_SERVER['REQUEST_TIME_FLOAT'] is not available

What it means

This exception is thrown by ResourceUsageFormatter::resourceUsageSinceStartOfRequest() when the superglobal $_SERVER['REQUEST_TIME_FLOAT'] is not set. The library uses that value (the timestamp the request started, provided by PHP's SAPI) to compute how much time/resources the request has consumed. Without it, no duration can be calculated, so the method fails fast with TimeSinceStartOfRequestNotAvailableException.

Solutions

1. Check isset($_SERVER['REQUEST_TIME_FLOAT']) (and that it is a float) before calling resourceUsageSinceStartOfRequest(), and fall back to a manually recorded start time when absent
2. Use the alternative ResourceUsageFormatter::resourceUsage(Duration $duration) API with a Duration you build yourself (e.g. Duration::fromMicroseconds((microtime(true) - $start) * 1000000)) when not in a request context
3. Only call resourceUsageSinceStartOfRequest() from genuine HTTP request handling code; in CLI code, capture your own start timestamp instead

Example fix

// before
$usage = $formatter->resourceUsageSinceStartOfRequest();

// after
if (isset($_SERVER['REQUEST_TIME_FLOAT']) && is_float($_SERVER['REQUEST_TIME_FLOAT'])) {
    $usage = $formatter->resourceUsageSinceStartOfRequest();
} else {
    $start = microtime(true);
    // ... work ...
    $usage = $formatter->resourceUsage(\SebastianBergmann\Timer\Duration::fromMicroseconds((microtime(true) - $start) * 1000000));
}

if (!isset($_SERVER['REQUEST_TIME_FLOAT'])) {
    // not in an HTTP request context; use a manual start time instead
}

function hasRequestTimeFloat(): bool
{
    return isset($_SERVER['REQUEST_TIME_FLOAT']) && is_float($_SERVER['REQUEST_TIME_FLOAT']);
}

use SebastianBergmann\Timer\TimeSinceStartOfRequestNotAvailableException;

try {
    $usage = $formatter->resourceUsageSinceStartOfRequest();
} catch (TimeSinceStartOfRequestNotAvailableException $e) {
    $usage = $formatter->resourceUsage(Duration::fromMicroseconds((microtime(true) - $fallbackStart) * 1000000));
}

When it happens

Trigger: Calling resourceUsageSinceStartOfRequest() in a context where PHP never populates $_SERVER['REQUEST_TIME_FLOAT'] — most commonly CLI scripts (phpunit, workers, cron jobs) instead of an HTTP/SAPI request context.

Common situations: Running PHPUnit or a CLI command that reuses web-oriented formatting code; executing code via a custom runner or daemon where the SAPI does not set REQUEST_TIME_FLOAT; unit tests that invoke the formatter with a minimal/empty $_SERVER array.

Understand the failure class

Background: "environment variable is not set" and "Missing keys in environment" errors: what missing required env var messages mean and how to fix them — this error's family across 28 libraries.

Related errors

• Cannot determine time at which the request started because…
• Timer::start() has to be called before Timer::stop()

AI-assisted analysis of sebastianbergmann/php-timer@3efcdcf213 (2026-09-13). Data as JSON: /api/errors/2a8a146bcbb42b49. Report an issue: GitHub.

Appendix: source

Thrown at src/ResourceUsageFormatter.php:43

        'KB' => 1024,
    ];

    public function resourceUsage(Duration $duration): string
    {
        return sprintf(
            'Time: %s, Memory: %s',
            $duration->asString(),
            $this->bytesToString(memory_get_peak_usage(true)),
        );
    }

    /**
     * @throws TimeSinceStartOfRequestNotAvailableException
     */
    public function resourceUsageSinceStartOfRequest(): string
    {
        if (!isset($_SERVER['REQUEST_TIME_FLOAT'])) {
            throw new TimeSinceStartOfRequestNotAvailableException(
                'Cannot determine time at which the request started because $_SERVER[\'REQUEST_TIME_FLOAT\'] is not available',
            );
        }

        if (!is_float($_SERVER['REQUEST_TIME_FLOAT'])) {
            throw new TimeSinceStartOfRequestNotAvailableException(
                'Cannot determine time at which the request started because $_SERVER[\'REQUEST_TIME_FLOAT\'] is not of type float',
            );
        }

        return $this->resourceUsage(
            Duration::fromMicroseconds(
                (1000000 * (microtime(true) - $_SERVER['REQUEST_TIME_FLOAT'])),
            ),
        );
    }

    private function bytesToString(int $bytes): string

View on GitHub (pinned to 3efcdcf213)