说明

Garbage collects unfinished XA transactions.

The XA protocol is a blocking protocol. There exist cases when servers participating in a global transaction cannot make progress when the transaction coordinator crashes or disconnects. In such a case, the MySQL servers keep waiting for instructions to finish the XA transaction in question. Because transactions occupy resources, transactions should always be terminated properly.

Garbage collection requires configuring a state store to track global transactions. Should a PHP client crash in the middle of a transaction and a new PHP client be started, then the built-in garbage collection can learn about the aborted global transaction and terminate it. If you do not configure a state store, the garbage collection cannot perform any cleanup tasks.

The state store should be crash-safe and be highly available to survive its own crash. Currently, only MySQL is supported as a state store.

Garbage collection can also be performed automatically in the background. See the plugin configuration directive garbage_collection for details.

Note: Experimental

The feature is currently under development. There may be issues and/or feature limitations. Do not use in production environments.