cmake find_package slow due to finding the same package multiple times

Question

I have a C++ project built using CMake like this way:

• The top level project adds each sub module by calling add_subdirectory
• and each sub module add its own sub modules by calling add_subdirectory
• and in the end, the sub module calls setup_src function, where find_package is called to search different dependencies.
• Some of the dependencies are the same but used by different modules
• Question: I would like to avoid find_package for the same dependeny multiple times for different modules, how can I do that?

To give you a big picture, here is the cmake tracing visualization for investigating this issue.

More Details

I have a C++ project built with CMake, and this project has many sub modules, which has similar project structure, and I use CMake's add_subdirectory to add each sub module and their own sub modules recursively.

In each sub module, I have a CMake function setup_src, where I call find_package for searching for this sub module's dependencies. Some of the dependencies are shared by multiple sub modules, I find the overall CMake configuration process slow (17 seconds), and I did some profiling and found the find_package for the same shared dependencies multiple times, which makes the configuration slow. For example, modA depends on find_package(gRPC) and modB also depends on find_package(gRPC), and I expected the second find_package(gRPC) either not happen or be very fast, but it turns out not the case.

I tried to avoid the second time find_package for the same dependency by using additional guard criteria in CMake since I assumed modA already found gRPC and modB doesn't have to find it again, but errors are reported by CMake saying something like CMake Error at xxxx.cmake:578 (_add_library): Target "zzz" links to target "yyy::yyy" but the target was not found. Perhaps a find_package() call is missing for an IMPORTED target, or an ALIAS target is missing?, and I know yyy is a transitive dependency for the shared dependency (gRPC in the example), but it is not clear to me how I can avoid finding the same package multiple times while not running into this issue.

Any help is appreciated. Thanks.