[pgpool-general: 7102] Fwd: Strange behavior after failover

Radosław Szczygieł radoslaw.szczygiel at interia.pl
Mon Jun 22 20:20:27 JST 2020


My apologize for text format. Im sending below message without html format


--
Pozdrawiam
Radosław Szczygieł

> 
> Hi PGPOOL TEAM,
> I have strange behavior of pgpool after failover.
> 
> My pgpool-pg cluster is:
> 2xPgpool 4.1, 2xPG 12.1 (streaming replication)
> 
> PGpool conf:
> 
> # - Concurrent session and pool size -
> num_init_children = 600
> 
 # Number of concurrent sessions allowed
> 
# (change requires restart)
> max_pool = 5
>  # Number of connection pool caches per connection
> 
# (change requires restart)
> # - Life time -
> 
> child_life_time = 1080
> 
>  # Pool exits after being idle for this many seconds
> child_max_connections = 2900
> 
# Pool exits after receiving that many connections

# 0 means no exit
> 
> connection_life_time = 840
>
 # Connection to backend closes after being idle for this many seconds
> 
 # 0 means no close
> client_idle_limit = 600
> 
> After failover from master ip .. 72 (node 0) to new master ip ..73 (node 1) and rebuild old master to new slave there were strange behavior of connections and transactions.  
> Before failover there were about 1500 connections per backend.
> After failover and rebuild slave there were almost 3000 connections per backend and many of connections to databases were on max level of Pgpool num_init_children parameter.
> 
> Also on new slave I've got many warnings from transations "WARNING:  there is no transaction in progress" like PGPOOL send sql COMMIT; to slave.
> 
> I had to make failover again to state before last failover because I was afraid of this situation. Logs looks normal but there was something wrong with closing connections to backends and this abnormal behavior of transations.
> Please look on screenshot from connections graph. Its shot from last failover where was bad state to normal state (master ip ..73 node 1 to new master ip ..72 node 0).
> Do You know something about problems with connections after failover?
> 
> pgpool1.png is graph all of connections to backend moment of last failover to normal state
> pgpool3.png is graph from one of databases moment of last failover to normal state
> 
> --
> Pozdrawiam 
> Radosław Szczygieł 

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