Clase 8 - “A New Age of JVM Garbage Collectors”

 “A New Age of JVM Garbage Collectors”

In this exposition, the presenter talks first about why a garbage collector is necessary for any programing language. And to be honest for any programmer understanding this is quite basic and can be resumed to 2 phrases. All programs generate united use of memory and memory is a finite resource. So for these 2 simple reasons we need a garbage collector. 

Now to get into the juicy part of the presentation we are going to analyze the different types of garbage collectors that are presented. The first and more basic one is manual memory management; it is hard to even consider this a garbage collector as it is done by the user. It is mostly used in the C language and works with a pointer to allocate and deallocate memory. 

Getting now into more interesting garbage collectors, the next model is Automatic reference counting. This model is based on keeping track of how many times an object is referenced. As long as there is one reference the allocation has to be there, but as soon as the count is 0 it can deallocate that memory. It is considered a good garbage collector but still has some problems as fragmentation and Pitfalls.

Now let us consider some higher-level garbage collectors, we have Mark sweep compact GC; this is famously used by Java. It is based on tracking all live objects in the program and then deleting everything else. Different from the past garbage collectors we analyzed this mode dose compact the remaining memory to prevent fragmentation. This model can also be complemented with Evacuating GC which uses heaps of the same size to do the compaction.

If I had to have a conclusion about this talk is that garbage collectors are way more complex than I would have initially thought. They are all composed of several new and old ideas with hundreds of trade-offs along the way. After this talk, the only thing I am certain of is that I am extremely grateful the garbage collectors exist.