[Pgpool-general] pgpool connection issue

[Tatsuo Ishii]

From: Nimesh Satam <nimesh.satam at gmail.com>
Subject: [Pgpool-general] pgpool connection issue
Date: Thu, 13 Jan 2011 17:12:34 +0530
Message-ID: <AANLkTim_iA51ziJxBW_Tw441qN8dCV3x9779PM07-zUR at mail.gmail.com>

> All,
> 
> We are facing connection problem while using pgpool-3.0.1 with
> postgres-9.0.1. One of the java application is trying to connect using
> pgpool, but after sometime the connection between the application seems to
> get hanged. This is leaving open connections on the database which are
> normally in "idle" or "idle in transaction state".
> 
> We re not running pgpool in debug mode hence dont have all the logs but
> below are few log entries which we get:
> 
> 2011-01-13 01:13:47 ERROR: pid 10567: wait_for_query_response: frontend
> error occured while waiting for backend reply
> 2011-01-13 01:13:47 LOG:   pid 10567: cancel_request: canceling backend
> pid:15798 key: 671497716
> 2011-01-13 01:13:47 ERROR: pid 10578: wait_for_query_response: frontend
> error occured while waiting for backend reply
> 2011-01-13 01:13:47 LOG:   pid 10578: cancel_request: canceling backend
> pid:22296 key: 979136593

Don't you get error messages something like:

pool_check_fd: select() failed. reason...

or 

pool_check_fd: exception occurred

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

> When we do a netstat between the server running the java process and the
> pgpool server, the connection status is shown as CLOSE_WAIT, even after
> killing the java process
> 
> Can someone highlight what might be going wrong.
> 
> Also below are the pgpool.conf file parameters
> 
> #
> # pgpool-II configuration file sample for Stream replication/Hot standby.
> # $Header: /cvsroot/pgpool/pgpool-II/pgpool.conf.sample-stream,v 1.5
> 2010/09/01 04:58:47 kitagawa Exp $
> 
> # Host name or IP address to listen on: '*' for all, '' for no TCP/IP
> # connections
> listen_addresses = '*'
> 
> # Port number for pgpool
> port = 9999
> 
> # Port number for pgpool communication manager
> pcp_port = 9898
> 
> # Unix domain socket path.  (The Debian package defaults to
> # /var/run/postgresql.)
> socket_dir = '/tmp'
> 
> # Unix domain socket path for pgpool communication manager.
> # (Debian package defaults to /var/run/postgresql)
> pcp_socket_dir = '/tmp'
> 
> # Unix domain socket path for the backend. Debian package defaults to
> /var/run/postgresql!
> backend_socket_dir = '/tmp'
> 
> # pgpool communication manager timeout. 0 means no timeout. This parameter
> is ignored now.
> pcp_timeout = 10
> 
> # number of pre-forked child process
> num_init_children = 60
> 
> # Number of connection pools allowed for a child process
> max_pool = 4
> 
> # If idle for this many seconds, child exits.  0 means no timeout.
> child_life_time = 300
> 
> # If idle for this many seconds, connection to PostgreSQL closes.
> # 0 means no timeout.
> connection_life_time = 0
> 
> # If child_max_connections connections were received, child exits.
> # 0 means no exit.
> child_max_connections = 0
> 
> # If client_idle_limit is n (n > 0), the client is forced to be
> # disconnected whenever after n seconds idle (even inside an explicit
> # transactions!)
> # 0 means no disconnect.
> client_idle_limit = 0
> 
> # Maximum time in seconds to complete client authentication.
> # 0 means no timeout.
> authentication_timeout = 60
> 
> # Logging directory
> logdir = '/var/log/pgpool'
> 
> # pid file name
> pid_file_name = '/var/run/pgpool/pgpool.pid'
> 
> # Replication mode
> replication_mode = false
> 
> # Load balancing mode, i.e., all SELECTs are load balanced.
> load_balance_mode = true
> 
> # If there's a disagreement with the packet kind sent from backend,
> # then degenrate the node which is most likely "minority".  If false,
> # just force to exit this session.
> replication_stop_on_mismatch = false
> 
> # If there's a disagreement with the number of affected tuples in
> # UPDATE/DELETE, then degenrate the node which is most likely
> # "minority".
> # If false, just abort the transaction to keep the consistency.
> failover_if_affected_tuples_mismatch = false
> 
> # If true, replicate SELECT statement when replication_mode or parallel_mode
> is enabled.
> # A priority of replicate_select is higher than load_balance_mode.
> replicate_select = false
> 
> # Semicolon separated list of queries to be issued at the end of a
> # session
> reset_query_list = 'ABORT; DISCARD ALL'
> # for 8.2 or older this should be as follows.
> #reset_query_list = 'ABORT; RESET ALL; SET SESSION AUTHORIZATION DEFAULT'
> 
> # white_function_list is a comma separated list of function names
> # those do not write to database. Any functions not listed here
> # are regarded to write to database and SELECTs including such
> # writer-functions will be executed on master(primary) in master/slave
> # mode, or executed on all DB nodes in replication mode.
> #
> # black_function_list is a comma separated list of function names
> # those write to database. Any functions not listed here
> # are regarded not to write to database and SELECTs including such
> # read-only-functions will be executed on any DB nodes.
> #
> # You cannot make full both white_function_list and
> # black_function_list at the same time. If you specify something in
> # one of them, you should make empty other.
> #
> # Pre 3.0 pgpool-II recognizes nextval and setval in hard coded
> # way. Following setting will do the same as the previous version.
> # white_function_list = ''
> # black_function_list = 'nextval,setval'
> white_function_list = ''
> black_function_list = 'nextval,setval'
> 
> # If true print timestamp on each log line.
> print_timestamp = true
> 
> # If true, operate in master/slave mode.
> master_slave_mode = true
> 
> # Master/slave sub mode. either 'slony' or 'stream'. Default is 'slony'.
> master_slave_sub_mode = 'stream'
> 
> # If the standby server delays more than delay_threshold,
> # any query goes to the primary only. The unit is in bytes.
> # 0 disables the check. Default is 0.
> # Note that health_check_period required to be greater than 0
> # to enable the functionality.
> delay_threshold = 10000000
> 
> # 'always' logs the standby delay whenever health check runs.
> # 'if_over_threshold' logs only if the delay exceeds delay_threshold.
> # 'none' disables the delay log.
> log_standby_delay = 'if_over_threshold'
> 
> # If true, cache connection pool.
> connection_cache = false
> 
> # Health check timeout.  0 means no timeout.
> health_check_timeout = 20
> 
> # Health check period.  0 means no health check.
> health_check_period = 10
> 
> # Health check user
> health_check_user = 'postgres'
> 
> # Execute command by failover.
> # special values:  %d = node id
> #                  %h = host name
> #                  %p = port number
> #                  %D = database cluster path
> #                  %m = new master node id
> #                  %M = old master node id
> #                  %% = '%' character
> #
> failover_command = '/usr/local/etc/failover.sh %d "%h" %p %D %m %M "%H" %P'
> 
> # Execute command by failback.
> # special values:  %d = node id
> #                  %h = host name
> #                  %p = port number
> #                  %D = database cluster path
> #                  %m = new master node id
> #                  %M = old master node id
> #                  %% = '%' character
> #
> failback_command = '/bin/rm -f /tmp/trigger_file1'
> 
> # If true, trigger fail over when writing to the backend communication
> # socket fails. This is the same behavior of pgpool-II 2.2.x or
> # earlier. If set to false, pgpool will report an error and disconnect
> # the session.
> fail_over_on_backend_error = true
> 
> # If true, automatically locks a table with INSERT statements to keep
> # SERIAL data consistency.  If the data does not have SERIAL data
> # type, no lock will be issued. An /*INSERT LOCK*/ comment has the
> # same effect.  A /NO INSERT LOCK*/ comment disables the effect.
> insert_lock = false
> 
> # If true, ignore leading white spaces of each query while pgpool judges
> # whether the query is a SELECT so that it can be load balanced.  This
> # is useful for certain APIs such as DBI/DBD which is known to adding an
> # extra leading white space.
> ignore_leading_white_space = true
> 
> # If true, print all statements to the log.  Like the log_statement option
> # to PostgreSQL, this allows for observing queries without engaging in full
> # debugging.
> log_statement = false
> 
> # If true, print all statements to the log. Similar to log_statement except
> # that prints DB node id and backend process id info.
> log_per_node_statement = false
> 
> # If true, incoming connections will be printed to the log.
> log_connections = false
> 
> # If true, hostname will be shown in ps status. Also shown in
> # connection log if log_connections = true.
> # Be warned that this feature will add overhead to look up hostname.
> log_hostname = true
> 
> # if non 0, run in parallel query mode
> parallel_mode = false
> 
> # if non 0, use query cache
> enable_query_cache = false
> 
> #set pgpool2 hostname
> pgpool2_hostname = ''
> 
> # system DB info
> system_db_hostname = 'localhost'
> system_db_port = 5432
> system_db_dbname = 'pgpool'
> system_db_schema = 'pgpool_catalog'
> system_db_user = 'pgpool'
> system_db_password = ''
> 
> # backend_hostname, backend_port, backend_weight
> # here are examples
> backend_hostname0 = '10.0.0.225'
> backend_port0 = 5432
> backend_weight0 = 1
> backend_data_directory0 = '/home/postgres/data'
> backend_hostname1 = '10.0.0.226'
> backend_port1 = 5432
> backend_weight1 = 0
> backend_data_directory1 = '/home/postgres/data'
> 
> # - HBA -
> 
> # If true, use pool_hba.conf for client authentication.
> enable_pool_hba = false
> 
> # - online recovery -
> # online recovery user
> recovery_user = 'postgres'
> 
> # online recovery password
> recovery_password = 'pgpoolAdmin'
> 
> # execute a command in first stage.
> recovery_1st_stage_command = 'basebackup.sh'
> 
> # execute a command in second stage.
> recovery_2nd_stage_command = ''
> 
> # maximum time in seconds to wait for the recovering node's postmaster
> # start-up. 0 means no wait.
> # this is also used as a timer waiting for clients disconnected before
> # starting 2nd stage
> recovery_timeout = 90
> 
> # If client_idle_limit_in_recovery is n (n > 0), the client is forced
> # to be disconnected whenever after n seconds idle (even inside an
> # explicit transactions!) in the second stage of online recovery.
> # n = -1 forces clients to be disconnected immediately.
> # 0 disables this functionality(wait forever).
> # This parameter only takes effect in recovery 2nd stage.
> client_idle_limit_in_recovery = 0
> 
> # Specify table name to lock. This is used when rewriting lo_creat
> # command in replication mode. The table must exist and has writable
> # permission to public. If the table name is '', no rewriting occurs.
> lobj_lock_table = ''
> 
> # If true, enable SSL support for both frontend and backend connections.
> # note that you must also set ssl_key and ssl_cert for SSL to work in
> # the frontend connections.
> ssl = false
> # path to the SSL private key file
> #ssl_key = './server.key'
> # path to the SSL public certificate file
> #ssl_cert = './server.cert'
> 
> # If either ssl_ca_cert or ssl_ca_cert_dir is set, then certificate
> # verification will be performed to establish the authenticity of the
> # certificate.  If neither is set to a nonempty string then no such
> # verification takes place.  ssl_ca_cert should be a path to a single
> # PEM format file containing CA root certificate(s), whereas ssl_ca_cert_dir
> # should be a directory containing such files.  These are analagous to the
> # -CAfile and -CApath options to openssl verify(1), respectively.
> #ssl_ca_cert = ''
> #ssl_ca_cert_dir = ''
> 
> # Debug message verbosity level. 0: no message, 1 <= : more verbose
> debug_level = 0
> 
> 
> Regards,
> Nimesh.