Under Advanced Test Properties, enable the Extended JMeterEngine resources configuration option.
JMeter in the Cloud default configuration includes running a single JMeter console on a dedicated server and additional servers running two JMeterEngine(s) on each. As each server is equipped with a dual core CPU and 1.7GB of memory, we limit the memory available for the console to 1GB and for each JMeterEngine to 512MB. In most cases this configuration should be more than enough. That said, JMeter will treat scripts differently according to their intensity and memory consumption.
For example let's consider two scripts:
Intense: 200 threads, doing 100 samples per thread with almost no delay between each sample.
Moderate: 300 threads, doing 10 samples per threads with few seconds delay between each sample.
JMeter will find the Intense script harder to execute compared to the Moderate script. The reason is that the Intense script requires more resources in terms of CPU power and memory than the Moderate one.
JMeter can suffocate under intensive scripts. One can easily see if his or hers script is too intensive for the available resources. Memory problems will appear in the logs.
For the purpose of more intensive scripts we provide an extended resources configuration. With this configuration each JMeterEngine runs on a dedicated server. The memory available for the JMeterEngine is limited to 1.5GB, triple the amount provided by the default configuration. Because this configuration uses one server per one JMeterEngine it requires additional Computing Hours compared to the default configuration.