I've found what had caused YourKit 2014/2015 startup crashes my OSX 10.10. Maybe someone might find this info useful.
My YourKit was constantly crashing with "EXC_BAD_ACCESS (SIGABRT)". In the thread dump I've noticed java trying to get a list of available input methods.
It turned out that I've had a custom keyboard layout installed in "~/Library/Keyboard Layouts". As soon as I disabled it in the keyboard preferences the problem went away.
Actually, it's a known problem of the Mac native launcher that it crashes on some machines at exactly this line. At the time of the investigation we didn't know a way to reproduce the crash locally although received multiple crash reports from different users, so thanks for suggesting ~/Library/Keyboard Layouts.
Anyway, the profiler UI since build 14112 is able to automatically restart using yjp.sh in case the native launcher crashes. Did this happen for you?