Infinite pool error event

[eugene2005]

Here is the code

import * as sql from 'mssql';

const pool = new sql.ConnectionPool(config.msSqlConfig);

pool.connect(error => {
    if (error) {
        logger.crit('Database connection error.', error.toString());
    }
});

pool.on('error', error => {
    if (error) {
        logger.crit('Pool error.', error.toString());
    }
});

function registerUser(user) {
    return pool.request()
        .input('name', Sql.SqlTypes.NVarChar(255), user.name)
        .input('email', Sql.SqlTypes.NVarChar(255), user.email)
        .input('password', Sql.SqlTypes.NVarChar(Sql.SqlTypes.MAX), user.password)
        .execute('registerUser')
        .then(result => {
        })
        .catch(error => {
           logger.crit('Query error.', error.toString());
        });
}

When the pool is initialized connection is available. Once connection is established I intentionally shutdown Sql Server and try to execute registerUser.
Here is what I get in my log:
...
2017-05-04 15:13:15 EDT - crit: Pool error. ConnectionError: Failed to connect to 192.168.1.116:1433 - connect ECONNREFUSED 192.168.1.116:1433
2017-05-04 15:13:16 EDT - crit: Pool error. ConnectionError: Failed to connect to 192.168.1.116:1433 - connect ECONNREFUSED 192.168.1.116:1433
2017-05-04 15:13:16 EDT - crit: Pool error. ConnectionError: Failed to connect to 192.168.1.116:1433 - connect ECONNREFUSED 192.168.1.116:1433
2017-05-04 15:13:17 EDT - crit: Pool error. ConnectionError: Failed to connect to 192.168.1.116:1433 - connect ECONNREFUSED 192.168.1.116:1433
2017-05-04 15:13:17 EDT - crit: Pool error. ConnectionError: Failed to connect to 192.168.1.116:1433 - connect ECONNREFUSED 192.168.1.116:1433
...
Messages never stop. It just keeps loging errors indefinitly.
If I don't sign up for pool error event I get
UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 2): ConnectionError: Failed to connect to 192.168.1.116:1433 - connect ECONNREFUSED 192.168.1.116:1433

[ruimgoncalves]

I have something similar, in my case ESOCK error when the network goes down.
Has a workaround I managed to break the loop by throwing an exception in the pool.on('error' ...

pool.on('error', error => {
   this.err = error
   throw new Error('Socket error, thown expcetion to prevent error loop')
})

[Halt001]

Can you explain where you catch that exception?

[dhensby]

This is due to a problem with thee way generic-pool tries to acquire good connections. It is now fixed in v5 (by adding a retry backoff) and v6 (by removing generic-pool)

[dhensby]

see #808 and #806

Also duplicate of #470