[Pgpool-general] pgbench hangs with pgpool II when count of connection is bigger than num_init_children

[Pavel Stehule]

Hello

thank you for explanation

Regards
Pavel Stehule

On 16/04/2008, Yoshiyuki Asaba <y-asaba at sraoss.co.jp> wrote:
> Hi,
>
>  From: "Pavel Stehule" <pavel.stehule at gmail.com>
>  Subject: [Pgpool-general] pgbench hangs with pgpool II when count of connection is bigger than num_init_children
>  Date: Wed, 16 Apr 2008 12:31:05 +0200
>
>
>  > I am testing pgpool II. I have small problem. If I understand to
>  > documentation well, then pg_pool can create num_init_children *
>  > max_pool connection. For default connection this is  128 connection.
>  >
>  > But when I check pgbench with 33 connection, then pgbench hangs
>
>
> It seems that you set num_init_children to 32. num_init_children is
>  the number of concurrent clients.
>
>   client-1  <--> pgpool-1
>   client-2  <--> pgpool-2
>   ...
>   client-32 <--> pgpool-32
>
>  client-33 waits until another client disconnects.
>
>  ex)
>  pgpool.conf:
>   num_init_children = 1
>   max_pool = 1
>
>   % pgpool -n
>
>  psql:
>   # client-1
>   % psql -p 9999 pool
>   Welcome to psql 8.3.0, the PostgreSQL interactive terminal.
>
>   Type:  \copyright for distribution terms
>          \h for help with SQL commands
>          \? for help with psql commands
>          \g or terminate with semicolon to execute query
>          \q to quit
>
>   pool=#
>
>   # client-2
>   % psql -p 9999 pool
>   wait...
>
>
>  max_pool is the number of connection cache slots in each
>  worker. Connection slots are mapped by user name and database name.
>
>            | <---> PostgreSQL (user: x, database: y)
>   pgpool-1 | <---> PostgreSQL (user: x, database: z)
>            | <---> PostgreSQL (user: y, database: z)
>            | <---> PostgreSQL (user: y, database: y)
>   ...
>            | <---> PostgreSQL (user: x, database: y)
>   pgpool-32| <---> PostgreSQL (user: x, database: z)
>            | <---> PostgreSQL (user: y, database: z)
>            | <---> PostgreSQL (user: y, database: y)
>
>  If slot is full, pgpool discards the oldest cache and creates a new
>  connection cache.
>
>  Regards,
>
> --
>  Yoshiyuki Asaba
>  y-asaba at sraoss.co.jp
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