The Java language (in which YAAC is written) works on the concept of a “heap” of available memory that can be doled out in pieces and the individual pieces returned to the heap when done using them. However, if a large amount of memory is allocated from the heap and not returned, the program can become extremely slow or even freeze up entirely when trying to allocate more memory for even simple operations (such as executing menu commands).
YAAC uses heap memory long-term to:
Most other uses of the heap are short-term and should not cause a strain on the available memory; the only major exceptions are the OpenStreetMap dataset importers, which are used very infrequently (if ever) by most users.
If you are seeing the “Reaching heap limit, lowering message retention limit” dialog, it means that the heap is running out of available memory. YAAC will attempt to protect itself by adjusting the one parameter under YAAC's own control, which is how long to keep old message traffic in memory before deleting those messages as obsolete.
However, if you are:
-Xmxcommand-line option, for example
java -Xmx512m -jar YAAC.jar
would start YAAC with a heap limit of 512 megabytes. You can specify any number here, but do not specify less than the system default, and it is recommended not to specify more than half the total physical memory in your computer (to allow some memory for your operating system and the parts of the Java runtime that are not counted against the heap limit).
If you have been starting YAAC by double-clicking on the YAAC.jar
file in your system's file explorer, you will need to set up a
desktop shortcut where you can explicitly specify the java invocation
command to include the memory limit option, using the
to invoke the Java runtime for a windowed desktop program.