[pgpool-committers: 5530] 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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V3_4_STABLE

Details
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https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=b92e0484d9bce7fd7dded79af200f520e57820b2

Modified Files
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src/protocol/pool_connection_pool.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)