[pgpool-committers: 5531] pgpool: Fix unnecessary fsync to pgpool_status file.

[Tatsuo Ishii]

Fix unnecessary fsync to pgpool_status file.

Whenever new connections are created to PostgreSQL backend, fsync()
was issued to pgpool_status file, which could generate excessive I/O
in certain conditions, for example num_init_children is large and
connections to backend have certain life time limit.

So reduce the chance of issuing fsync() so that it is issued only when
backend status is changed from CON_CONNECT_WAIT or others to CON_UP.
If the status is already CON_UP, we don't need to write to
pgpool_status.

Discussion: [pgpool-general: 6436] High I/O Usage on PGPool nodes

Branch
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V4_0_STABLE

Details
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https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=6224e9a52ee1e766b1698dbd5f74c841d4c3bcf4

Modified Files
--------------
src/protocol/pool_connection_pool.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)