What can be tuned in garbage collection? What are the goals of different GCs?

In Java's garbage collector (GC), several parameters can be configured to optimize performance and memory management:

• Heap sizes: initial (-Xms) and maximum (-Xmx) heap sizes affect the frequency and duration of garbage collections.
• Generation parameters (Young, Old generation): sizes and ratios between young and old generations can be tuned to optimize collection frequency and type.
• Garbage collector type: choosing between Serial, Parallel, CMS, G1, ZGC, and others, each aims for different goals — minimizing pauses, maximizing throughput, low memory consumption, etc.
• Pause and thread parameters: number of GC threads, trigger thresholds, behavior during fragmentation.

Goals of different GCs:

• Minimize pauses (Low Latency): for example, CMS or ZGC aim to reduce application stop time.
• Maximum throughput: Parallel GC is optimized for maximum performance, sacrificing pauses.
• Balance between pauses and throughput: G1 GC tries to find a compromise by managing the heap in regions.

Tuning GC allows adapting the collector's behavior to specific application requirements — balancing response time and resource usage.