G1 asserts with

G1: assert(rp->num_q() == no_of_gc_workers) failed: sanity

running the following program

public class GCTest {
  private static byte[] garbage;
  public static void main(String [] args) {
    System.out.println("Creating garbage");
    // create 128MB of garbage. This should result in at least one GC
    for (int i = 0; i < 1024; i++) {
      garbage = new byte[128 * 1024];
    }
    System.out.println("Done");
  }
}

with

-Xmx10m -XX:+UseG1GC -XX:+UseDynamicNumberOfGCThreads -XX:+ParallelRefProcEnabled

Seems to be a re-appearance of JDK-8055250.

Reported by G. Lindenmaier in the following mail to hotspot-gc-dev:

http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2016-February/016481.html

The suggestion there is to add this case to gc/ergonomics/TestDynamicNumberOfGCThreads.java