Free Memory (RapidMiner Studio Core)


This operator frees unused memory. It might be useful after large preprocessing chains with a lot of currently unused views or even data copies.


The Free Memory operator cleans up unused memory resources. It might be very useful in combination with the Materialize Data operator after large preprocessing trees using a lot of views or data copies. It can be very useful after the data set was materialized in memory. Internally, this operator simply invokes a garbage collection from the underlying Java programming language.

Please note that RapidMiner keeps data sets in memory as long as possible. So if there is any memory left, RapidMiner will not discard previous results of the process or data at the port. The Free Memory operator can be useful if you get the OutOfMemoryException. Also note that operators like the Remember operator put the objects in the Store. The Free Memory operator does not clean up the store. This operator will only free memory which is no longer needed which is not the case if the object is in the Store.

After process execution has been completed, everything including the Stores is freed, but only if needed! So you can take a look at your previous results in the Result History as long as they fit into the memory. RapidMiner will automatically discard all these Results if a currently running process or new result needs free memory. So the memory usage will constantly grow with the time until it has reached a peak value and RapidMiner starts to discard previous results.


  • through (Data Table)

    It is not compulsory to connect any object with this port. Any object connected at this port is delivered without any modifications to the output port. This operator can have multiple inputs. When one input is connected, another through input port becomes available which is ready to accept another input (if any). The order of inputs remains the same. The object supplied at the first through input port of the Free Memory operator is available at the first through output port.


  • through (Data Table)

    The objects that were given as input are passed without changing to the output through this port. It is not compulsory to attach this port to any other port, the memory is freed even if this port is left without connections. The Free Memory operator can have multiple outputs. When one output is connected, another through output port becomes available which is ready to deliver another output (if any). The order of outputs remains the same. The object delivered at the first through input port of the Free Memory operator is delivered at the first through output port

Tutorial Processes

Introduction to the Free Memory operator

This is a very simple Example Process which just shows how to use the Free Memory operator. First the Subprocess operator is applied. Suppose we have a memory intensive task in the subprocess and we want to free unused memory after the subprocess is complete. The Free Memory operator is applied after the Subprocess operator to free the unused memory. No memory intensive task is performed in this Example Process. This Process was intended to discuss only the way this operator can be applied. Please make sure that the operators are applied in correct sequence. Also note that the Free Memory operator is not connected to any other operator but still it can perform its task.