df27c5b76f
Both Percona and Maria allow MySQL to be configured to listen on an extra port when their thread pool is enable. * https://www.percona.com/doc/percona-server/5.7/performance/threadpool.html * https://mariadb.com/kb/en/the-mariadb-library/thread-pool-in-mariadb-51-53/ This is valuable because if the table has a lot of traffic (read or write load), gh-ost can end up starving the thread pool as incomming connections are immediately blocked. By using gh-ost on the extra port, MySQL locking will still behave the same, but MySQL will keep a dedicated thread for each gh-ost connection. When doing this, it's important to inspect the extra-max-connections variable. Both Percona and Maria default to 1, so gh-ost may easily exceed with its threads. An example local run using this ``` $ mysql -S /tmp/mysql_sandbox20393.sock -e "select @@global.port, @@global.extra_port" +---------------+---------------------+ | @@global.port | @@global.extra_port | +---------------+---------------------+ | 20393 | 30393 | +---------------+---------------------+ ./bin/gh-ost \ --initially-drop-ghost-table \ --initially-drop-old-table \ --assume-rbr \ --port="20395" \ --assume-master-host="127.0.0.1:30393" \ --max-load=Threads_running=25 \ --critical-load=Threads_running=1000 \ --chunk-size=1000 \ --max-lag-millis=1500 \ --user="gh-ost" \ --password="gh-ost" \ --database="test" \ --table="mytable" \ --verbose \ --alter="ADD mynewcol decimal(11,2) DEFAULT 0.0 NOT NULL" \ --exact-rowcount \ --concurrent-rowcount \ --default-retries=120 \ --panic-flag-file=/tmp/ghost.panic.flag \ --postpone-cut-over-flag-file=/tmp/ghost.postpone.flag \ --execute ``` |
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| .. | ||
| applier.go | ||
| hooks.go | ||
| inspect.go | ||
| migrator.go | ||
| server.go | ||
| streamer.go | ||
| throttler.go | ||