# Measuring Script Run Time

Append `/start` to a ping URL and use it to signal when a job starts. After receiving a start signal, Healthchecks.io will show the check as "Started." It will store the "start" events and display the job execution times. SITE_NAME calculates the job execution times as the time gaps between adjacent "start" and "success" events.

## Alerting Logic

SITE_NAME applies an additional alerting rule for jobs that use the `/start` signal.

If a job sends a "start" signal, but then does not send a "success" signal within its configured grace time, SITE_NAME will assume the job has failed. It will mark the job as "down" and send out alerts.

## Usage Example

Below is a code example in Python:

    import requests
    URL = "PING_URL"

    # "/start" kicks off a timer: if the job takes longer than
    # the configured grace time, the check will be marked as "down"
    try:
        requests.get(URL + "/start", timeout=5)
    except requests.exceptions.RequestException:
        # If the network request fails for any reason, we don't want
        # it to prevent the main job from running
        pass

    # TODO: run the job here
    fib = lambda n: n if n < 2 else fib(n - 1) + fib(n - 2)
    print("F(42) = %d" % fib(42))

    # Signal success:
    requests.get(URL)

## Viewing Measured Run Times

When SITE_NAME receives a "start" signal followed by a regular ping or a "fail" signal, and the two events are less than 24 hours apart, you will see the time delta displayed in the list of checks. If the two events are more than 24 hours apart, they are assumed to be unrelated, and the time delta is not displayed.

You can also see durations of the previous runs when viewing an individual check: