IssueDcacheTooManySQLConnections

Symptoms

SE cannot be accessed through srm.

• In t3se01:catalina.out: createConnection(): Got exception org.postgresql.util.PSQLException, SQLState: 53300
• In t3cachedb01:pg_sql: FATAL:  connection limit exceeded for non-superusers

Occurrences

Observations

Number of connections is set up in /var/lib/pgsql/data/postgresql.conf: max_connections. From the manual it can be seen that to raise that number it could be necessary to modify the SysV parameter SEMMNI.

It is not clear why the 100 limit is reached. Probably, a certain number of transfers fails and leaves hanged connections on the db level, piling up until the limit is reached. A Nagios plot about this will be created (Fabio) to monitor this pile-up effect.

Solution or Workaround

A clean restart of dcache on se01,following the instructions reported here: StartStopDcache. This cured the issue all the times.

Monitoring for this condition

A check for number of DB connections will be inserted in Nagios

-- LeonardoSala - 2011-11-28

-- DerekFeichtinger - 29 Aug 2008