C++ and Java did exist, and rejected for the following reasons:
"Furthermore, the existing Apache tools depended on Java - specifically the JVM - where it's really hard to get predictable, very low latency results."
"From a purely performance perspective, C or C++ would have been a good choice. However, from past experience we knew that building highly distributed data processing applications in C/C++ was no easy task. We ruled out C++ because we wanted better safety guarantees around memory and concurrency."