File descriptor leak bug

When running this the client we see file descriptor leaks. The client continually recreates a channel and a stub, which is probably not the recommended behaviour?

The leak is observed when building against the latest versions of grpc (1.18) and protoc (3.6.1) fetched by the vcpkg package manager.

When building against the latest grpc/cxx Docker image, the leak is not present. The image contains grpc 1.10.x (based on this dockerfile and protoc 3.5.0.

Reproducing the bug

Start either with the latest grpc/cxx docker image, or Debian Stretch with build essentials installed.

Install vcpkg:

git clone https://github.com/Microsoft/vcpkg.git
cd vcpkg
./bootstrap-vcpkg.sh
sudo ./vcpkg integrate install
./vcpkg install fftw3 protobuf cppzmq grpc

cd /usr/local/bin
sudo ln -s ${HOME}/vcpkg/vcpkg vcpkg
Add following to .bashrc file: "export VCPKG_ROOT=${HOME}/vcpkg"

Check out this repo and run cmake

git clone https://github.com/IzakMarais/grpc-bug.git
cd grpc-bug
mkdir build
cd build
${VCPKG_ROOT}/downloads/tools/cmake-3.12.4-linux/cmake-3.12.4-Linux-x86_64/bin/cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_TOOLCHAIN_FILE=${VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake ../
make

Run the route_guide_server and route_guide_client in separate terminals. In a third terminal do

ls /proc/`pidof route_guide_client`/fd

One can see that the number of file descriptors increases after each rpc call the client made.

Bug not present when built against grpc/cxx docker image

If we just check out the repo in the grpc/cxx Docker and run make, the bug is not present.

git clone https://github.com/IzakMarais/grpc-bug.git
cd grpc-bug
make

Run the route_guide_client and route_guide_server in separate terminals. In a third terminal do

ls /proc/`pidof route_guide_client`/fd

One can see that the number of file descriptors remain constant.