Ceph » mgr

The progress module does get('pg_stats'), which does

  } else if (what == "pg_stats") {
    return cluster_state.with_pgmap([&](const PGMap &pg_map) {
      with_gil_t with_gil{no_gil};
      pg_map.dump_pg_stats(&f, false);
      return f.get();
    });

This hold ClusterState::lock for a looong time while PyFormatter generates a zillion objects for a full dump of PGMap over all PGs. This can take a long time (multiple seconds) on large clusters, which ends up blocking the ms_dispatch thread and/or reports that are coming in from osds etc.