How does Parrot compare to other virtual machines?

Question

Parrot is the virtual machine originally designed for Perl 6.

What technical capabilities does the Parrot VM offer that competing virtual machines such as the Java Virtu

Answer 1

Parrot is the virtual machine originally designed for Perl 6.

There are now two VMs originally designed for Perl 6; commits to MoarVM began in 2012.

What technical capabilities does the Parrot VM offer that competing virtual machines such as the Java Virtual Machine (JVM)/Hotspot VM and Common Language Runtime (CLR) lack?

In another answer on this page, Reini Urban, the current (April 2015) Parrot lead dev, provides a brief comparison of Parrot with the JVM and CLR VM.

According to Reini, a key advantage Parrot has over MoarVM is "effectively lock-less threads".