[pgpool-hackers: 3856] Misleading documentation

[Tatsuo Ishii]

While taking care of this:
https://www.pgpool.net/mantisbt/view.php?id=671

I noticed our documentation gives misleading explanation about pgpool
behavior when pgpool.conf is reloaded:

https://www.pgpool.net/docs/latest/en/html/config-setting.html#CONFIG-SETTING-CONFIGURATION-FILE
The configuration file is reread whenever the main server process
receives a SIGHUP signal; this signal is most easily sent by running
pgpool reload from the command line. The main pgpool process also
propagates this signal to all its child processes, so that existing
sessions also adopt the new values. Some parameters can only be set at
server start; any changes to their entries in the configuration file
will be ignored until the server is restarted. Invalid parameter
settings in the configuration file are likewise ignored (but logged)
during SIGHUP processing.

The reality is, new parameter values will not be reflected to existing
sessions. They will be reflected when new session is
established. Reloading new config values is handled by
check_config_reload() in src/protocol/child.c. It's only called in the
beginning of establishing client sessions. It will not be called while
the session continues. Changing the place to call the function so that
it is called within a session maybe possible. But it will need
careful investigation to not break existing logic depending on
parameters.

So I am going to change the documentation to reflect the behavior of
current implementation for now. Attached is the patch.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp
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