When I run the following Node.js script with node-oracledb 6.0's default 'Thin' mode, I see a delay/pause of a few seconds before it finally terminates.
const oracledb = require('oracledb');
const dbConfig = require('./dbconfig.js');
async function runApp() {
const connection = await oracledb.getConnection(dbConfig);
const result = await connection.execute(`select * from dual`);
console.dir(result.rows, { depth: null });
console.log('not closing connection');
// console.log('closing connection');
// await connection.close();
}
runApp();
Note that I do not explicitly close the connection here. When I include connection.close(), the pause/delay goes away.
To demonstrate this issue with/without closing the connection, I use the time command in my Linux machine:
$ time node t.js
[ [ 'X' ] ]
closing connection
real 0m0.249s
user 0m0.082s
sys 0m0.017s
$ time node t.js
[ [ 'X' ] ]
not closing connection
real 0m8.187s
user 0m0.092s
sys 0m0.017s
I did not see this delay in the earlier node-oracledb version, irrespective of whether I closed connections or not. What is the reason?
This behavior with node-oracledb 6.0's Thin mode is expected. It is due to the open connection reference needing to be cleaned up by the garbage collector.
In node-oracledb 6.0's thin mode, the sockets are known to the event loop and will keep the application running until these sockets are closed. Internally there is a finalization registry that forces these sockets to be closed when the object holding them is garbage collected. However, in thick mode or the earlier node-oracledb versions, the sockets are held by the Oracle Client library. So, Node.js pays no attention to them and is quite happy to terminate with them still open!