GC info

[arakov]

Add possibility to view gc statistics

[arakov]

The following code can be used to retrieve GC statistics:

import extensions;
import extensions'runtime;

public program() 
{
   console.printLine("before:");
   SystemMonitor.printMemoryStatistics();

   var n := 0;
   while (n < 100000) {
      n := n + 1;
   };
   
   console.printLine("after:");
   SystemMonitor.printMemoryStatistics();
}

SystemMonitor.printMemoryStatistics will print the info:

before:
=== Memory usage statistics ===
yg allocated:      180
yg free:           14E80
mg allocated:      0
mg free:           2A000
perm allocated:    0
perm free:         0
minor collections: 0
major collections: 0
===============================
after:
=== Memory usage statistics ===
yg allocated:      FF90
yg free:           5070
mg allocated:      0
mg free:           2A000
perm allocated:    0
perm free:         0
minor collections: 12
major collections: 0
===============================