Counters

    Use counters to generate incrementing values, such as unique identifiers

    Counters store an incrementing value into the virtual user’s Session. Use them for example to generate unique identifiers, without having to write a custom feeder or function.

    The name you pass to counter is the name of the Session attribute that’s set when a virtual user reaches this action. In the example below, each virtual user reaching the counter gets the next value stored in its Session under the id attribute, which you can then use anywhere, for example with the Gatling EL expression #{id}.

           
    exec(counter("id").startingAt(1).withIncrement(10).upTo(100));
    exec(counter("id").startingAt(1).withIncrement(10).upTo(100));
    exec(counter("id").startingAt(1).withIncrement(10).upTo(100))
    exec(counter("id").startingAt(1).withIncrement(10).upTo(100))

    Configure a counter

    Method Description Default
    startingAt The first value to emit. Must be positive. 0
    withIncrement The gap between 2 successive values. 1
    upTo The exclusive upper bound, except for Integer.MAX_VALUE. When reached, the load generator stops, unless you use wrapAround. Integer.MAX_VALUE

    Wrap around at the upper bound

    By default, Gatling stops the load generator when the counter reaches its upper bound. Use wrapAround to start over from the first value instead.

           
    exec(counter("id").upTo(100).wrapAround());
    exec(counter("id").upTo(100).wrapAround());
    exec(counter("id").upTo(100).wrapAround())
    exec(counter("id").upTo(100).wrapAround)

    Track a counter for each virtual user

    By default, all the virtual users of a load generator share one single sequence of values. Use perUser to track the counter independently for each virtual user, so they all get the very same sequence.

    Only in this mode, startingAt, withIncrement and upTo accept a Gatling EL string or a function instead of a static value. Otherwise, building the Simulation fails.

           
    exec(counter("id").perUser().startingAt("#{startingAt}"));
    exec(counter("id").perUser().startingAt("#{startingAt}"));
    exec(counter("id").perUser().startingAt("#{startingAt}"))
    exec(counter("id").perUser.startingAt("#{startingAt}"))

    Keep values unique across a cluster

    When running with Gatling Enterprise, use shard to distribute the values evenly amongst all the load generators, so they remain unique cluster wide. Each load generator only gets a slice of the range, so the values emitted by the whole cluster have holes. Outside of Gatling Enterprise, shard has no effect.

           
    exec(counter("id").shard());
    exec(counter("id").shard());
    exec(counter("id").shard())
    exec(counter("id").shard)

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