Martin Buchholz suggested the topic and Mikael signed up to lead the session. Martin gave an introduction. He had observed some issues recently (“impossible null pointer exceptions”) which after investigation turned out to be caused by a toolchain upgrade and in turn revealed the fact that some code in hotspot requires atomicity but does not make this requirement very explicit and in the end assumes that the C++ compiler will produce suitable code to guarantee atomicity. Martin also observed that (on linux) hotspot is compiled targeting the c++98 standard, which is old enough to not even mention the concept of threads. Mikael also added that for extra fun the story is different on different platforms and toolchains.