5.2.0 started only using master instead of slaves

[archon810]

Following up on: #172 (comment).

We just put in the code on a dev server that outputs all the db servers used, and indeed, with 5.2.0 only the master is output, whereas with previous versions as well as humanmade 5.0.6 we are getting random slave read servers, as desired.

You asked me to put in the config. Here it is, with the comments stripped out:

<?php

$wpdb->charset = 'utf8mb4';
$wpdb->collate = 'utf8mb4_unicode_ci';
$wpdb->save_queries = defined('SAVEQUERIES') && SAVEQUERIES;
$wpdb->persistent = false;
$wpdb->max_connections = 500;
$wpdb->check_tcp_responsiveness = false;

$wpdb->add_database(array(
    'host'     => DB_HOST,     // If port is other than 3306, use host:port.
    'user'     => DB_USER,
    'password' => DB_PASSWORD,
    'name'     => DB_NAME,
    'read'     => 3,
    'write'     => 1,
    'timeout'  => 0.2,
));

//If $enable_hyperdb_slaves is true
global $enable_hyperdb_slaves;
global $enable_hyperdb_slaves_in_admin;
if ($enable_hyperdb_slaves) {
    //Only enable slaves if we are not in wp-admin, or if we are and $enable_hyperdb_slaves_in_admin is true
  if (($enable_hyperdb_slaves_in_admin && is_admin()) || !is_admin()) {
      /**
     * This adds the same server again, only this time it is configured as a slave.
     * The last three parameters are set to the defaults but are shown for clarity.
     */
    $wpdb->add_database(array(
        'host'     => 'slave1',     // If port is other than 3306, use host:port.
        'user'     => DB_USER,
        'password' => DB_PASSWORD,
        'name'     => DB_NAME,
        'write'    => 0,
        'read'     => 2,
        'dataset'  => 'global',
        'timeout'  => 0.2,
     // 'lag_threshold' => 1,
    ));

    /**
     * This adds the same server again, only this time it is configured as a slave.
     * The last three parameters are set to the defaults but are shown for clarity.
     */
    $wpdb->add_database(array(
      'host'     => 'slave2',     // If port is other than 3306, use host:port.
      'user'     => DB_USER,
      'password' => DB_PASSWORD,
      'name'     => DB_NAME,
      'write'    => 0,
      'read'     => 2,
      'dataset'  => 'global',
      'timeout'  => 0.2,
     // 'lag_threshold' => 1,
    ));

    /**
     * This adds the same server again, only this time it is configured as a slave.
     * The last three parameters are set to the defaults but are shown for clarity.
     */
    $wpdb->add_database(array(
      'host'     => 'slave3',     // If port is other than 3306, use host:port.
      'user'     => DB_USER,
      'password' => DB_PASSWORD,
      'name'     => DB_NAME,
      'write'    => 0,
      'read'     => 2,
      'dataset'  => 'global',
      'timeout'  => 0.2,
     // 'lag_threshold' => 1,
    ));
  }
}

The correct version is showing up in Drop-ins:

And the db.php symlink is correct:

db.php -> mu-plugins/ludicrousdb/ludicrousdb/drop-ins/db.php

Any ideas?

[JJJ]

Thank you. This is helpful. I'll diff the tags, find where things went wrong, and get this fixed over the weekend.

[archon810]

@JJJ Did you have a chance to take a crack at this yet?

[JJJ]

I did start reviewing the changes & diffs, and I setup a new group of docker containers to test your configuration with.

My next step, I think, is to git bisect until I can pinpoint which commit introduced the problem, because nothing is standing out to my eyes.

(Ultimately, I'd love to use that rig to automate some tests so I don't break this again.)

[archon810]

The main question is whether you can reproduce it yourself. Were you able to?

[JJJ]

No, but only because I don't have a multi-read setup that I can test on right now; that is what my new docker container group will (hopefully) address.

[archon810]

@JJJ Have you had a chance to give that new setup a try?