The following small program makes parallel GC perform a seemingly endless sequence of GCs.
I ran on Mac and linux with the same result.

---
import java.util.ArrayList;

public class AllocTest {
   public static ArrayList list = new ArrayList(0);

   public static void main(String[] args) {
      for (int i = 0; i < 10 * 1024 * 1024; i++) {
         list.add(new byte[30]);
      }
   }
}
---

java -XX:+PrintGC -XX:-UseAdaptiveSizePolicy AllocTest
[GC (Allocation Failure) 33792K->28014K(125952K), 0.0159740 secs]
[GC (Allocation Failure) 57731K->58010K(125952K), 0.0184900 secs]
[GC (Allocation Failure) 89106K->90940K(125952K), 0.0205580 secs]
[Full GC (Ergonomics) 90940K->80370K(125952K), 0.2297420 secs]
[Full GC (Ergonomics) 114162K->107244K(125952K), 0.2776750 secs]
[Full GC (Ergonomics) 120289K->120266K(125952K), 0.2023220 secs]
[Full GC (Ergonomics) 134401K->125174K(140288K), 0.1813880 secs]
[Full GC (Ergonomics) 134902K->134901K(140288K), 0.2124570 secs]
[Full GC (Ergonomics) 134902K->134902K(140288K), 0.1825430 secs]
[Full GC (Ergonomics) 134902K->134902K(140288K), 0.1843810 secs]
[Full GC (Ergonomics) 134905K->134905K(140288K), 0.1871200 secs]
[Full GC (Ergonomics) 134908K->134908K(140288K), 0.1813770 secs]
[Full GC (Ergonomics) 134911K->134911K(140288K), 0.1871500 secs]
[Full GC (Ergonomics) 134914K->134914K(140288K), 0.1865300 secs]
[Full GC (Ergonomics) 134917K->134917K(140288K), 0.1832800 secs]
[Full GC (Ergonomics) 134920K->134920K(140288K), 0.1804150 secs]
[Full GC (Ergonomics) 134923K->134923K(140288K), 0.1820260 secs]
[Full GC (Ergonomics) 134926K->134926K(140288K), 0.1818820 secs]
[Full GC (Ergonomics) 134929K->134929K(140288K), 0.1838340 secs]
[Full GC (Ergonomics) 134932K->134932K(140288K), 0.1810300 secs]
[Full GC (Ergonomics) 134935K->134935K(140288K), 0.1814470 secs]
[Full GC (Ergonomics) 134938K->134938K(140288K), 0.1833440 secs]
[Full GC (Ergonomics) 134941K->134941K(140288K), 0.1912060 secs]
[Full GC (Ergonomics) 134944K->134944K(140288K), 0.1818990 secs]
[Full GC (Ergonomics) 134947K->134947K(140288K), 0.1810360 secs]
[Full GC (Ergonomics) 134950K->134950K(140288K), 0.1867140 secs]
[Full GC (Ergonomics) 134953K->134953K(140288K), 0.1840500 secs]
[Full GC (Ergonomics) 134956K->134956K(140288K), 0.1847880 secs]
[Full GC (Ergonomics) 134959K->134959K(140288K), 0.1800580 secs]
[Full GC (Ergonomics) 134962K->134962K(140288K), 0.1804830 secs]
[Full GC (Ergonomics) 134965K->134965K(140288K), 0.1817410 secs]
[Full GC (Ergonomics) 134968K->134968K(140288K), 0.1828290 secs]
[Full GC (Ergonomics) 134971K->134970K(140288K), 0.1840240 secs]
[Full GC (Ergonomics) 134973K->134973K(140288K), 0.1829350 secs]
[Full GC (Ergonomics) 134976K->134976K(140288K), 0.1835530 secs]
[Full GC (Ergonomics) 134979K->134979K(140288K), 0.1810700 secs]
[Full GC (Ergonomics) 134982K->134982K(140288K), 0.1802410 secs]
[Full GC (Ergonomics) 134985K->134985K(140288K), 0.1815830 secs]
[Full GC (Ergonomics) 134988K->134988K(140288K), 0.1821900 secs]
[Full GC (Ergonomics) 134991K->134991K(140288K), 0.1816480 secs]
[Full GC (Ergonomics) 134994K->134994K(140288K), 0.1804760 secs]
[Full GC (Ergonomics) 134997K->134997K(140288K), 0.1800450 secs]
[Full GC (Ergonomics) 135000K->135000K(140288K), 0.1813470 secs]
[Full GC (Ergonomics) 135003K->135003K(140288K), 0.1818470 secs]
[Full GC (Ergonomics) 135006K->135006K(140288K), 0.1837830 secs]
[Full GC (Ergonomics) 135009K->135009K(140288K), 0.1840300 secs]
...