using a faster libunwind on linux for LSAN_OPTIONS=fast_unwind_on_malloc=false ?

Hey there,

I'm regularly using LSAN on user applications where some third party
dependencies are compiled without framepointers (and without sanitizers). In
such cases, the leak reports from LSAN are usually garbage, and the fix is to
use `LSAN_OPTIONS=fast_unwind_on_malloc=false`. But that comes at a hefty
performance price, which makes it infeasible for me to have it enabled all the

I wonder - would it be possible to use libunwind [1] (not the one from LLVM),
or alternatively improve the LLVM-libunwind to apply similar caching


I'm using libunwind in heaptrack, where I also record backtraces for every
single heap allocation. I have the feeling that the performance impact of that
is much lower compared to using `LSAN_OPTIONS=fast_unwind_on_malloc=false`.

Has this ever been discussed?