Hi,
I am looking for some advice on memory usage on mobile devices, BlackBerry in particular. Using some profiling tools we have calculated a working set size in RAM of 525kb. Problem is we don't really know whether this is acceptable or too high.
Can anyone give any insight into their own experience with memory usage on BlackBerry? What sort of number should we be aiming for?
I'm also wondering what sort of things we should be looking out for in particular to reduce memory usage.
TIA
If I'm not mistaken, Blackberry apps are written in Java... which is a managed environment, which means really the only surefire way to use less memory is to create fewer objects. There's not a whole lot you can do about your working set, I think, since it's managed by the runtime (which is actually probably the point of using Java on devices like this).
512KB is perfectly acceptable on the current generation of BlackBerrys devices. You can take a look at JBenchmark to see the exact JVM heap you can expect for each model, but none of the current devices out there go below 20MB of heap. Most are much larger than that.
On JBenchmark you can choose the device you are interested from a drop down on the right side of the page. Then, navigate to the JVM Tab for the device.
When it comes to reducing memory usage I wouldn't worry about the total bytes used for this application if you are truly inline with 525K, just about how often allocation/reallocation is required. Try to pool/reuse objects as much as possible, avoiding any unneeded allocation. For instance, use the StringBuffer class to concatenate strings instead of operators as multiple String objects will be created for each concatenation using the operator, where a StringBuffer will just put the characters in an array and only expand when needed. Google is a good way to find more tips.
Finally, relying on profiling tools, which the BlackBerry JDE has, is a very important part of understanding exactly how you can optimize heap memory usage.