In the main OASIS screen, you may see the following bar. This is the memory usage monitor. It keeps track of the memory used by the software.
If you click on the bar, you can see a summary of the memory available/used.
Why is the "Current memory" different than what my OS's process manager shows? (Technical info)
If you are viewing the memory utilization of OASIS in something such as Task Manager (Windows) or Activity Monitor (OS X), you will see a value reported as the current memory used by OASIS (sometimes it will show as "java"). This value here is the total memory that the Java Virtual Machine (JVM) has claimed from the OS.
Most of the time, this value will be different from what is actually used inside the application. When objects in memory are freed up, the JVM does not free up what it has claimed from the OS; rather, it keeps that space assuming it will need to use that in the future. Even though the memory is freed up inside the JVM, the JVM is still using the previous memory. This is normal behavior for all processes running in a JVM, such as OASIS.
Why do I sometimes get a "Out of Memory" error?
In these scenarios, you are likely running into a situation where the Free Memory has reached 0. This free memory can be viewed in the memory monitor above. When a JVM reaches it's max memory allowed (something that is enforced when launching the JVM), it will throw an OutOfMemory error. Usually this can be fixed by either restarting the process (e.g. OASIS) or by launching the program with a larger max-memory threshold (we usually refer to this second method as launching OASIS in "1G", "2G", or "4G").