"Tom Lane" <tgl@sss.pgh.pa.us> wrote
>
> "postgres --single" works for me. Maybe you need a "make
> distclean"/rebuild?
>

Sorry, because I forget to say that you need to turn "stats_command_string"
on. When it is off, pgstat_report_activity() will return immediately so
nothing wrong could be observed.

Regards,
Qingqing