Handle fork in target application (#191)

* Always print PID in log messages

* omnitrace-dl updates

- omnitrace_preload does not call omnitrace_init or omnitrace_init_tooling
- omnitrace_preload will call omnitrace_set_mpi if OMNITRACE_USE_MPI
  or OMNITRACE_USE_MPIP in the env is true but not call it otherwise
  because doing so either overrides OMNITRACE_USE_PID (when true) or
  disable mpip from initialization (when false) and the MPI
  init can be caught later and override OMNITRACE_USE_PID

* config updates

- set_setting_value sets user update type
- remove volatile from get_settings_configured
- don't override settings::default_process_suffix
- don't kill process in omnitrace_exit_action
- set_state ignores updating state if >= State::Finalized

* Handle state > State::Finalized

* fork gotcha updates

- unsets LD_PRELOAD
- sets OMNITRACE_ROOT_PROCESS
- sets OMNITRACE_CHILD_PROCESS

* libomnitrace library.cpp updates

- basic_bundle for fini metrics
- handle finalization from child process

* sampling updates

- sampling::shutdown handles when child process

* Add example and test using fork

* Update run-ci script to support not submitting

* Tweak test envs

* Update build flags when codecov enabled

* remove unnecessary includes of sampling header

* Replace mpi copy/fini static lambda with free-funcs

* Update codecov job

* Fix OMPT segfaults after finalization

* Miscellaneous updates after rebase

* fixes for causal profiling

* revert some run-ci.sh changes

* Disable storing env in sampling::shutdown

* formatting fix

* Update timemory submodule

- fixed occasional synchronization issues with allocator offloading
- exclude protozero:: from internal samples

* improve root/child process detection

- avoid omnitrace_finalize in MPI when child process
- revert some testing tweaks

source/lib/omnitrace/library/runtime.cpp

@@ -35,6 +35,7 @@
 #include <timemory/backends/threading.hpp>
 #include <timemory/components/rusage/backends.hpp>
 #include <timemory/environment.hpp>
+#include <timemory/process/process.hpp>
 #include <timemory/sampling/allocator.hpp>
 #include <timemory/settings.hpp>
 #include <timemory/settings/types.hpp>
@@ -55,6 +56,8 @@ namespace omnitrace
 {
 namespace
 {
+auto root_process_id = get_env<pid_t>("OMNITRACE_ROOT_PROCESS", process::get_id(), false);
+
 auto&
 get_sampling_on_child_threads_history(int64_t _idx = utility::get_thread_index())
 {
@@ -259,4 +262,22 @@ set_sampling_on_all_future_threads(bool _v)
     for(size_t i = 0; i < max_supported_threads; ++i)
         get_sampling_on_child_threads_history(i).emplace_back(_v);
 }
+
+pid_t
+get_root_process_id()
+{
+    return root_process_id;
+}
+
+bool
+is_root_process()
+{
+    return (root_process_id == process::get_id());
+}
+
+bool
+is_child_process()
+{
+    return (root_process_id != process::get_id());
+}
 }  // namespace omnitrace