PgBouncer

　PgBouncer は、PostgreSQL へのコネクションをプールして、接続時間や接続を管理するのに必要なリソースを、劇的に減少させる事ができる。

libevent のインストール

libevent より libevent をダウンロードする。

$ mkdir ~/work
$ cd ~/work
$ curl -L -O https://sourceforge.net/projects/levent/files/libevent/libevent-2.0/libevent-2.0.22-stable.tar.gz

ファイルを解凍する。

$ tar zxvf libevent-2.0.22-stable.tar.gz

libevent のビルドとインストールを行う。

$ cd libevent-2.0.22-stable
$ ./configure
$ make
$ sudo make install

libevent をシステムに登録するための定義ファイルを作成する。
```
$ sudo vi /etc/ld.so.conf.d/libevent2-x86_64.conf
```
```
/usr/local/lib/
```
libevent をシステムに登録する。
```
$ sudo ldconfig
```

PgBouncer のインストール

PgFoundry: PgBouncer: ファイルリストより PgBouncer をダウンロードする。

$ mkdir ~/work
$ cd ~/work
$ curl -O http://pgfoundry.org/frs/download.php/3393/pgbouncer-1.5.4.tar.gz

ファイルを解凍する。
```
$ tar zxvf pgbouncer-1.5.4.tar.gz
```

PgBouncer のビルドとインストールを行う。

$ cd pgbouncer-1.5.4
$ ./configure --prefix=/usr/local --with-libevent=/usr/local
$ make
$ sudo make install

ディレクトリを作成する。

$ sudo mkdir -p /var/log/pgbouncer
$ sudo mkdir -p /var/run/pgbouncer

実行ユーザーを作成する。
```
$ sudo useradd pgbouncer
```

オーナーを設定する。

$ sudo chown pgbouncer:pgbouncer /var/log/pgbouncer
$ sudo chown pgbouncer:pgbouncer /var/run/pgbouncer

rc スクリプトを作成する。

$ sudo vi /etc/rc.d/init.d/pgbouncer

#!/bin/sh
# pgbouncer    This is the init script for starting up the pgbouncer
#
# chkconfig: - 64 36
# description: Starts and stops the pgbouncer daemon.
#
# processname: pgbouncer
# pidfile: /var/run/pgbouncer/pgbouncer.pid
#
# v2.0 Devrim GUNDUZ <devrim@CommandPrompt.com>
# - Adjust order of startup and kill.
#
# v2.1 Devrim GUNDUZ <devrim@gunduz.org>
# - Fix chkconfig line
# - Start pgbouncer in daemon mode, so that it won't log twice
# - to the same log file.
#
# v2.2 Devrim GUNDUZ <devrim@gunduz.org>
# - Sleep 2 seconds before getting pid during start(), like
#   we do in PostgreSQL init script, to avoid false positive
#   startup errors.

# Source function library.
INITD=/etc/rc.d/init.d
. $INITD/functions

# Get function listing for cross-distribution logic.
TYPESET=`typeset -f|grep "declare"`

# Get config.
. /etc/sysconfig/network

# Find the name of the script
NAME=`basename $0`
if [ ${NAME:0:1} = "S" -o ${NAME:0:1} = "K" ]
then
        NAME=${NAME:3}
fi

# For SELinux we need to use 'runuser' not 'su'
if [ -x /sbin/runuser ]
then
    SU=runuser
else
    SU=su
fi

# Override defaults from /etc/sysconfig/pgbouncer if file is present
[ -f /etc/sysconfig/${NAME} ] && . /etc/sysconfig/${NAME}

# Check that networking is up.
[ "${NETWORKING}" = "no" ] && exit 0

script_result=0

start(){
        BOUNCER_START=$"Starting ${NAME} service: "

        # Make sure startup-time log file is valid
        if [ ! -e "$BOUNCERLOG" -a ! -h "$BOUNCERLOG" ]
        then
                touch "$BOUNCERLOG" || exit 1
                chown pgbouncer:pgbouncer "$BOUNCERLOG"
                chmod go-rwx "$BOUNCERLOG"
                [ -x /usr/bin/chcon ] && /usr/bin/chcon -u system_u -r object_r -t postgresql_log_t "$BOUNCERLOG" 2>/dev/null
        fi

        # Make sure that pgbouncer is not already running:
        if [ -f /var/run/${NAME}/${NAME}.pid ]
        then
                echo "${NAME} is already running"
                echo_failure
                echo
                exit 1
        fi

        echo -n "$BOUNCER_START"
        [ -d /var/run/${NAME} ] || mkdir /var/run/${NAME}
        chown pgbouncer:pgbouncer /var/run/${NAME}

        $SU -l pgbouncer -c "pgbouncer -d '$BOUNCERCONF' & " >> "$BOUNCERLOG" 2>&1 < /dev/null
        sleep 2
        pid=`pidof -s pgbouncer`
        if [ $pid ]
        then
          success "$BOUNCER_START"
          touch /var/lock/subsys/${NAME}
          echo
        else
          failure "$BOUNCER_START"
          echo
          script_result=1
        fi
}

stop(){
        echo -n $"Stopping ${NAME} service: "
        if [ -f /var/run/${NAME}/${NAME}.pid ]
        then
                kill -TERM `cat "/var/run/${NAME}/${NAME}.pid"`
                ret=$?
                if [ $ret -eq 0 ]
                then
                        echo_success
                else
                        echo_failure
                        script_result=1
                fi
                echo
                  rm -f "/var/run/${NAME}/${NAME}.pid"
                  rm -f "/var/lock/subsys/${NAME}"
        else
                echo "   ${NAME} is not running."
                echo_failure
                echo
                exit 1
        fi
}

restart(){
    stop
    start
}

condrestart(){
    [ -e /var/lock/subsys/${NAME} ] && restart
}

condstop(){
    [ -e /var/lock/subsys/${NAME} ] && stop
}

reload(){
    $SU -l pgbouncer -c "kill -HUP `cat /var/run/${NAME}/${NAME}.pid`" > /dev/null 2>&1 < /dev/null
}
pause(){
    $SU -l pgbouncer -c "kill -USR1 `cat /var/run/${NAME}/${NAME}.pid`" > /dev/null 2>&1 < /dev/null
}
resum(){
   $SU -l pgbouncer -c "kill -USR2 `cat /var/run/${NAME}/${NAME}.pid`" > /dev/null 2>&1 < /dev/null
}
# See how we were called.
case "$1" in
  start)
        start
        ;;
  stop)
        stop
        ;;
  status)
        status pgbouncer
        script_result=$?
        ;;
  restart)
        restart
        ;;
  pause)
        pause
        ;;
  continue)
        resum
        ;;
  condrestart)
        condrestart
        ;;
  condstop)
        condstop
        ;;
  reload|force-reload)
        reload
        ;;
  *)
        echo $"Usage: $0 {start|stop|status|restart|pause|continue|reload|force-reload|condrestart|condstop}"
        exit 1
esac

exit $script_result

rc スクリプトのパーミッションを設定する。
```
$ sudo chmod 755 /etc/rc.d/init.d/pgbouncer
```
自動起動の設定を行う。
```
$ sudo chkconfig pgbouncer on
```

デフォルト設定ファイルを作成して、設定ファイルとログファイルのパスを設定する。

$ sudo vi /etc/sysconfig/pgbouncer

#
# pgbouncer defaults
#

# Path to the init file
BOUNCERCONF=/etc/pgbouncer.ini

# Path to the log file
BOUNCERLOG=/var/log/pgbouncer/pgbouncer.log

の設定を行う。

$ sudo vi /etc/pgbouncer.ini

;; database name = connect string
;;
;; connect string params:
;;   dbname= host= port= user= password=
;;   client_encoding= datestyle= timezone=
;;   pool_size= connect_query=
[databases]
;template1 = host=pgsql.mydomain.net dbname=template1 user=pgadmin password=pgadmin pool_size=1
database_name1  = host=localhost dbname=database_name1 user=database_user1 password=password1
database_name2  = host=localhost dbname=database_name2 user=database_user2 password=password2
database_name3  = host=localhost dbname=database_name3 user=database_user3 password=password3

; foodb over unix socket
;foodb =

; redirect bardb to bazdb on localhost
;bardb = host=localhost dbname=bazdb

; acceess to dest database will go with single user
;forcedb = host=127.0.0.1 port=300 user=baz password=foo client_encoding=UNICODE datestyle=ISO connect_query='SELECT 1'

; use custom pool sizes
;nondefaultdb = pool_size=50 reserve_pool=10

; fallback connect string
;* = host=testserver

;; Configuration section
[pgbouncer]

;;;
;;; Administrative settings
;;;

logfile = /var/log/pgbouncer/pgbouncer.log
pidfile = /var/run/pgbouncer/pgbouncer.pid

;;;
;;; Where to wait for clients
;;;

; ip address or * which means all ip-s
listen_addr = 127.0.0.1
listen_port = 6432

user = pgbouncer

; unix socket is also used for -R.
; On debian it should be /var/run/postgresql
;unix_socket_dir = /tmp
;unix_socket_mode = 0777
;unix_socket_group =

;;;
;;; Authentication settings
;;;

; any, trust, plain, crypt, md5
;auth_type = trust
auth_type = any
;auth_file = /8.0/main/global/pg_auth
;auth_file = /etc/pgbouncer/userlist.txt

;;;
;;; Users allowed into database 'pgbouncer'
;;;

; comma-separated list of users, who are allowed to change settings
admin_users = postgres

; comma-separated list of users who are just allowed to use SHOW command
stats_users = stats, postgres

;;;
;;; Pooler personality questions
;;;

; When server connection is released back to pool:
;   session      - after client disconnects
;   transaction  - after transaction finishes
;   statement    - after statement finishes
;pool_mode = session
pool_mode = transaction

;
; Query for cleaning connection immediately after releasing from client.
; No need to put ROLLBACK here, pgbouncer does not reuse connections
; where transaction is left open.
;
; Query for 8.3+:
;   DISCARD ALL;
;
; Older versions:
;   RESET ALL; SET SESSION AUTHORIZATION DEFAULT
;
; Empty if transaction pooling is in use.
;
server_reset_query = DISCARD ALL

;
; Comma-separated list of parameters to ignore when given
; in startup packet.  Newer JDBC versions require the
; extra_float_digits here.
;
;ignore_startup_parameters = extra_float_digits

;
; When taking idle server into use, this query is ran first.
;   SELECT 1
;
;server_check_query = select 1

; If server was used more recently that this many seconds ago,
; skip the check query.  Value 0 may or may not run in immediately.
;server_check_delay = 30

;;;
;;; Connection limits
;;;

; total number of clients that can connect
;max_client_conn = 100
max_client_conn = 1000

; default pool size.  20 is good number when transaction pooling
; is in use, in session pooling it needs to be the number of
; max clients you want to handle at any moment
;default_pool_size = 20
default_pool_size = 100

; how many additional connection to allow in case of trouble
;reserve_pool_size = 5

; if a clients needs to wait more than this many seconds, use reserve pool
;reserve_pool_timeout = 3

; log if client connects or server connection is made
;log_connections = 1

; log if and why connection was closed
;log_disconnections = 1

; log error messages pooler sends to clients
;log_pooler_errors = 1


; If off, then server connections are reused in LIFO manner
;server_round_robin = 0

;;;
;;; Timeouts
;;;

;; Close server connection if its been connected longer.
;server_lifetime = 1200

;; Close server connection if its not been used in this time.
;; Allows to clean unnecessary connections from pool after peak.
;server_idle_timeout = 60

;; Cancel connection attempt if server does not answer takes longer.
;server_connect_timeout = 15

;; If server login failed (server_connect_timeout or auth failure)
;; then wait this many second.
;server_login_retry = 15

;; Dangerous.  Server connection is closed if query does not return
;; in this time.  Should be used to survive network problems,
;; _not_ as statement_timeout. (default: 0)
;query_timeout = 0

;; Dangerous.  Client connection is closed if the query is not assigned
;; to a server in this time.  Should be used to limit the number of queued
;; queries in case of a database or network failure. (default: 0)
;query_wait_timeout = 0

;; Dangerous.  Client connection is closed if no activity in this time.
;; Should be used to survive network problems. (default: 0)
;client_idle_timeout = 0

;; Disconnect clients who have not managed to log in after connecting
;; in this many seconds.
;client_login_timeout = 60

;; Clean automatically created database entries (via "*") if they
;; stay unused in this many seconds.
; autodb_idle_timeout = 3600

;;;
;;; Low-level tuning options
;;;

;; buffer for streaming packets
;pkt_buf = 2048

;; man 2 listen
;listen_backlog = 128

;; networking options, for info: man 7 tcp

;; Linux: notify program about new connection only if there
;; is also data received.  (Seconds to wait.)
;; On Linux the default is 45, on other OS'es 0.
;tcp_defer_accept = 0

;; In-kernel buffer size (Linux default: 4096)
;tcp_socket_buffer = 0

;; whether tcp keepalive should be turned on (0/1)
;tcp_keepalive = 1

;; following options are Linux-specific.
;; they also require tcp_keepalive=1

;; count of keepaliva packets
;tcp_keepcnt = 0

;; how long the connection can be idle,
;; before sending keepalive packets
;tcp_keepidle = 0

;; The time between individual keepalive probes.
;tcp_keepintvl = 0

;; DNS lookup caching time
;dns_max_ttl = 15

;; DNS zone SOA lookup period
;dns_zone_check_period = 0

サービスを起動する。
```
$ sudo service pgbouncer start
```

PgBouncer の使い方

バージョン確認

$ /usr/local/bin/pgbouncer -V

コマンドラインからデーモンとして起動

$ sudo /usr/local/bin/pgbouncer -d /etc/pgbouncer.ini

オンラインのまま再起動

$ sudo /usr/local/bin/pgbouncer -R -d /etc/pgbouncer.ini

参考文献

Postgres Plus ユーザーサイト - FAQ
Pgbouncer installation « Stan Santiago's blog
build libevent and transmission on RHEL/CentOS 5.x | geekery
libevent
PgFoundry: PgBouncer: ファイルリスト
 pgbouncerのインストール : 個人的なメモ帳

目次

PgBouncer

libevent のインストール

PgBouncer のインストール

PgBouncer の使い方

参考文献