Excessive disk usage in build directory - 4.4 GB

[PaulBouchier]

When building using the command line specified in the README.md,
colcon build --cmake-args -DCMAKE_BUILD_TYPE=Release
the build directory grows to 4.4 GB. This seems to be due to stuff in a couple of directories called debug way down in the build tree.

This problem causes issues on small platforms like Raspberry Pi (I ran out of space), and the requirement to give --cmake-args makes it not fit well into a standard workspace build, where you can just type colcon build.

Is there some short-term workaround to avoid the bloat? And can the build be made so that the default colcon build just does what it should?

[Yadunund]

@PaulBouchier thanks for the ticket. I can confirm the build dir for zenoh_cpp_vendor is ~4.3GB.

It's unclear whether this is "bloat" introduced by our build system or whether building Zenoh-c/cpp takes up this much space. We'd appreciate if you could investigate by building zenoh-cpp following the instructions upstream https://github.com/eclipse-zenoh/zenoh-cpp?tab=readme-ov-file#building-and-running-tests while passing along the flags as we do in rmw_zenoh,

rmw_zenoh/zenoh_cpp_vendor/CMakeLists.txt

Lines 18 to 40 in 2e43a48

	set(ZENOHC_CARGO_FLAGS "--no-default-features$<SEMICOLON>--features=shared-memory zenoh/transport_compression zenoh/transport_tcp zenoh/transport_tls")
	# Set VCS_VERSION to include latest changes from zenoh/zenoh-c/zenoh-cpp to benefit from :
	# - https://github.com/eclipse-zenoh/zenoh/pull/173 (Improve config to support priorities range in locators)
	# - https://github.com/eclipse-zenoh/zenoh/pull/1736, https://github.com/eclipse-zenoh/zenoh/pull/1735,
	# https://github.com/eclipse-zenoh/zenoh/pull/1744, https://github.com/eclipse-zenoh/zenoh/pull/1749,
	# https://github.com/eclipse-zenoh/zenoh/pull/1751 (Improve performance of a large number of peers)
	ament_vendor(zenoh_c_vendor
	VCS_URL https://github.com/eclipse-zenoh/zenoh-c.git
	VCS_VERSION 5fce7fb1d397e016ad02a50bde4262007d755424
	CMAKE_ARGS
	"-DZENOHC_CARGO_FLAGS=${ZENOHC_CARGO_FLAGS}"
	"-DZENOHC_BUILD_WITH_UNSTABLE_API=TRUE"
	"-DZENOHC_CUSTOM_TARGET=${ZENOHC_CUSTOM_TARGET}"
	)
	ament_export_dependencies(zenohc)
	ament_vendor(zenoh_cpp_vendor
	VCS_URL https://github.com/eclipse-zenoh/zenoh-cpp
	VCS_VERSION bd4d741c6c4fa6509d8d745e22c3c50b4306bd65
	CMAKE_ARGS
	-DZENOHCXX_ZENOHC=OFF

Anyways, building code from source on RPi will likely lead to resource constraints. Why not rely on rmw_zenoh binaries instead?

[PaulBouchier]

Thanks for the suggestion to use binaries. I did that and they work fine. I added README.md documentation about using binary packages to my PR. I'll respond here with findings from the investigation you requested.