What is GC and full GC?

Major GC is cleaning the Tenured space. Full GC is cleaning the entire Heap – both Young and Tenured spaces.

What is concurrent GC?

Microsoft’s “concurrent GC” is generational: it uses the stop-the-world strategy for only a limited part of the heap (what they call “generations 0 and 1”). Since that part remains small, pauses remain short (e.g. below 50ms), so that the user will not notice them.

What is Mark and sweep algorithm in Java?

The mark-and-sweep algorithm is called a tracing garbage collector because it traces out the entire collection of objects that are directly or indirectly accessible by the program. Example: a) All the objects have their marked bits set to false.

Why full GC is bad?

Full GC is an important event in the garbage collection process. During this full GC phase, garbage is collected from all the regions in the JVM heap (Young, Old, Perm, Metaspace). Full GC tends to evict more objects from memory, as it runs across all generations.

What triggers full GC?

A Full GC will be triggered whenever the heap fills up. In such a case the young generation is collected first followed by the old generation.

What are the drawbacks of the mark-sweep method?

The main disadvantage of the mark-and-sweep approach is the fact that that normal program execution is suspended while the garbage collection algorithm runs.

When to use Concurrent Mark Sweep ( CMS ) collector?

The Concurrent Mark Sweep (CMS) collector is designed for applications that prefer shorter garbage collection pauses and that can afford to share processor resources with the garbage collector while the application is running.

What is floating garbage in Concurrent mark sweep?

Such unreachable objects that haven’t yet been reclaimed are referred to as floating garbage. The amount of floating garbage depends on the duration of the concurrent collection cycle and on the frequency of reference updates, also known as mutations, by the application.

Which is worse parallel GC or Concurrent mark and sweep?

As most of the time at least some CPU resources are consumed by the GC and not executing your application’s code, CMS generally often worse throughput than Parallel GC in CPU-bound applications.

Which is longer concurrent preclean or concurrent sweep?

The concurrent phases (concurrent mark, concurrent preclean, and concurrent sweep) normally last significantly longer than a minor collection pause, as indicated in the CMS collector output example. Note, however, that the application isn’t paused during these concurrent phases.