io.vertx.sqlclient.ClosedConnectionException: the underlying connection may have been lost unexpectedly.

[fen-nec]

Version

5.0.0

Context

I have tried everything there is to remedy this: io.vertx.sqlclient.ClosedConnectionException: Failed to read any response from the server, the underlying connection may have been lost unexpectedly.

Trying to create a pool with bit of code that I call inside of a compose (loading the env file) in the mainverticle:

MySQLConnectOptions connectOptions = new MySQLConnectOptions()
  .setPort(3306)
  .setHost(this.appConfig.getString("MYSQL_HOST"))
  .setDatabase(this.appConfig.getString("MYSQL_DB"))
  .setUser(this.appConfig.getString("MYSQL_USER"))
  .setAuthenticationPlugin(MySQLAuthenticationPlugin.MYSQL_NATIVE_PASSWORD)
  .setPassword(this.appConfig.getString("MYSQL_PWD"));
PoolOptions poolOptions = new PoolOptions()
  .setMaxSize(5); // Configurable pool size

this.mySQLPool = MySQLBuilder
  .pool()
  .with(poolOptions)
  .connectingTo(connectOptions)
  .using(vertx)
  .build();

System.out.println("MySQL Pool initialized.");

this.mySQLPool.query("SELECT 1").execute()
  .onSuccess(rows -> System.out.println("Successfully connected to MySQL and executed a test query."))
  .onFailure(Throwable::printStackTrace);`

I have tried using version 4.5.7. Java 17, 21. I added/removed options. The same result.
I ran a test with the JDBC driver and it works fine.

Steps to reproduce

No response

Do you have a reproducer?

No response

[vietj]

which thread executes this ?

check the connection has not been closed in your test because it might have been garbage collected and closed

[fen-nec]

I have simplified my code to isolate the issue.

I tested with two databases: 10.5.27-MariaDB-ubu2004 (running in local docker container) and MySQL 5.5.9 (remote DB that I want to connect to).

I tested with vertx 5 and 4.5.15. (from https://start.vertx.io/)

This is my start method:

``@Override
public Future start() { Promise start = Promise.promise();
MySQLConnectOptions connectOptions = new MySQLConnectOptions()
.setAuthenticationPlugin(MySQLAuthenticationPlugin.MYSQL_NATIVE_PASSWORD)
.setPort(3306)
.setHost("localhost")
.setDatabase("db")
.setUser("root")
.setCharset("utf8mb4")
.setPassword("pwd");
PoolOptions poolOptions = new PoolOptions()
.setMaxSize(5);

Pool pool = MySQLBuilder
  .pool()
  .with(poolOptions)
  .connectingTo(connectOptions)
  .using(vertx)
  .build();

System.out.println("Pool init thread: " + Thread.currentThread().getName());

pool.query("SELECT VERSION() as version").execute()
  .onSuccess(rows -> {
    System.out.println("Successfully connected to MySQL and executed a test query." + rows.iterator().next().getString("version"));
    vertx.createHttpServer().requestHandler(req -> {
      req.response()
        .putHeader("content-type", "text/plain")
        .end("Hello from Vert.x!");
    }).listen(8888).onComplete(http -> {
      if (http.succeeded()) {
        System.out.println("HTTP server started on port 8888");
        start.complete();
      } else {
        start.fail(http.cause());
      }
    });
  })
  .onFailure(err -> {
    System.err.println(">>> FAILURE: Failed to connect to MySQL.");
    err.printStackTrace();
  });
return start.future();

}```

The results :
Vertx 4.15 / 5 connects to local DB but not remote one.

The version of mysql is 5.5.9 which according to the docs should be fine.
No SSL is required.

The thread is: vert.x-eventloop-thread-1 or similar (not that I think it is the thread since mariaDB worked)

Am I missing something ?

which thread executes this ?

check the connection has not been closed in your test because it might have been garbage collected and closed

[vietj]

can you move the pool outside of the method ?

[fen-nec]

Hi again, not sure what you are asking. The same code, two different databases: 10.5.27-MariaDB-ubu2004 and MySQL 5.5.9. The first one works, the other does not...I fail to see what moving the code around can do.