JVMCI initialization must happen exactly once and this is guaranteed by serializing on JVMCI.<clinit>. There is a guarantee in JVMCI VM code that guard against re-initialization but it's in the wrong place. This was shown (see attached hs_err log) by recent Graal changes[1].

[1] https://github.com/graalvm/graal-core/commit/13a235cf8e4278af5577d72da30058bfba426c98