The default allocator is whatever is provided by the platform libc. In this case, i would guess that's the glibc allocator. It's possible that the glibc alloca

The default allocator is whatever is provided by the platform libc. In this case, i would guess that's the glibc allocator. It's possible that the glibc allocator contains some simple bug. It's more likely that it doesn't contain any simple bugs, but makes different tradeoffs to jemalloc, which make it less suitable to this particular slice of applications.