Why Am I Getting the 'org.postgresql.util.PSQLException: FATAL: sorry, too many clients already' Error in My PostgreSQL Database?

Error: "org.postgresql.util.PSQLException: FATAL: sorry, too many clients already"

When attempting to connect to a Postgresql database, you may encounter this error message, indicating that the connection limit has been exceeded.

This error arises when your code exceeds the maximum allowed number of simultaneous connections to the Postgresql database. It typically occurs when multiple connections are opened within a loop without being properly closed using conn.close();. As a result, the connections are not released upon class destruction.

Fix:

To resolve this issue, implement the following steps:

1. Add the following code to all classes that create database connections:

protected void finalize() throws Throwable  
{  
    try { your_connection.close(); } 
    catch (SQLException e) { 
        e.printStackTrace();
    }
    super.finalize();  
}  

This code ensures that the connection is closed when the class is garbage collected.

2. Check the maximum allowed connections by running the following SQL:

show max_connections;

The default limit is 100. Adjust this value if necessary.

3. Identify and close any open connections that may be consuming resources:

SELECT * FROM pg_stat_activity;

Debugging:

1. Use an exception stack trace to track the source of connection creation.
2. Verify that every line where a connection is created is accompanied by a corresponding connection.close(); statement.

Increasing max_connections:

To increase the maximum number of connections allowed, locate the postgresql.conf file and edit the following line:

max_connections=100

Set this value to a larger number and restart the database.

Maximum max_connections:

Run the following query to determine the theoretical maximum number of connections:

select min_val, max_val from pg_settings where name='max_connections';

However, it is recommended to set a reasonable limit to prevent runaway processes from monopolizing connections.

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