The root cause of the ping timeout issue in Python that was recently reported by Dataflow as well as in issue #38282 was because Python has explicitly disabled the use of EventEngine polling using the GRPC_DO_NOT_INSTANTIATE_POSIX_POLLER build flag (Reference: #33279).
Removing the flag solves this issue, however, considering that it originally was added because of lack of fork support when using EventEngine, the current work in progress to add fork support using EventEngine must be completed before removing this flag.

In addition, it was also found that the issue could not be reproduced when running via Bazel. This was because the GRPC_DO_NOT_INSTANTIATE_POSIX_POLLER flag was not getting propagated upstream to the Core layer, unless specifically defined as a compiler option in tools/bazel.rc or passed in via command line

This PR hence includes the C++ server and client code to reproduce the ping timeout issue.

Steps to reproduce the ping timeout via Bazel in CPP:

• export GRPC_TRACE=tcp,http,http2_keepalive,http2_ping,polling,polling_api
• export GRPC_VERBOSITY=debug
• Run bazel run //examples/cpp/ping_timeout_repro:greeter_server --copt=-DGRPC_DO_NOT_INSTANTIATE_POSIX_POLLER to start the CPP server
• Run bazel run //examples/cpp/ping_timeout_repro:repro_greeter_client --copt=-DGRPC_DO_NOT_INSTANTIATE_POSIX_POLLER to start the CPP client

NOTE: The issue can only be reproduced when including the --copt flag via command line. Running the example as described above with the specific debug trace logs should show log lines such as:

I0000 00:00:1745420380.475681 3473830 chttp2_transport.cc:1963] ipv6:%5B::1%5D:50051: Ping timeout. Closing transport.
...
I0000 00:00:1745420380.476151 3473830 chttp2_transport.cc:1844] 0x7ffb90001600 CANCEL PINGS: UNKNOWN:ping timeout {grpc_status:14}
...
I0000 00:00:1745420380.477078 3473830 chttp2_transport.cc:1844] 0x7ffb90001600 CANCEL PINGS: UNKNOWN:goaway sent
...
I0000 00:00:1745420380.477298 3473830 ev_posix.cc:186] (polling-api) fd_shutdown(5)
...
I0000 00:00:1745420380.477517 3473830 tcp_posix.cc:1105] TCP:0x55a33ded8300 got_read: UNKNOWN:FD Shutdown {children:[UNAVAILABLE:endpoint shutdown]}