是否存在用于在一定时间后或在应用重启时自动删除LiquiBase DATABASE CHANGELOGLOCK的配置? [英] Is there a configuration for removing LiquiBase DATABASE CHANGELOGLOCK automatically after a certain time or on app restart?
问题描述
我们有SpringBoot 2驱动的HA Java应用程序，其中我们在下面使用PostgreSQL.
We have SpringBoot 2 driven HA java application in which we use PostgreSQL underneath.
由于诸如意外崩溃或异常之类的某些原因，Liquibase最终以陈旧的DATABASECHANGELOGLOCK锁定，从未释放.
For certain reasons like unexpected crashes or Exceptions, Liquibase ends up with a stale DATABASECHANGELOGLOCK which was never released.
这导致应用程序的后续部署失败，应用程序等待更改锁定，然后退出，如下所示:
This results in subsequent deployments of the app failing with app waiting for the change lock and then exiting as follows:
2020-03-04T11:10:31.78+0200 SELECT LOCKED FROM public.databasechangeloglock WHERE ID=1
2020-03-04T11:10:31.78+0200 Waiting for changelog lock....
2020-03-04T11:10:32.87+0200 SELECT LOCKED FROM public.databasechangeloglock WHERE ID=1
2020-03-04T11:10:32.87+0200 Waiting for changelog lock....
2020-03-04T11:10:41.78+0200 SELECT LOCKED FROM public.databasechangeloglock WHERE ID=1
2020-03-04T11:10:41.78+0200 Waiting for changelog lock....
2020-03-04T11:10:42.87+0200 SELECT LOCKED FROM public.databasechangeloglock WHERE ID=1
2020-03-04T11:10:42.87+0200 Waiting for changelog lock....
2020-03-04T11:10:51.79+0200 SELECT LOCKED FROM public.databasechangeloglock WHERE ID=1
2020-03-04T11:10:51.79+0200 Waiting for changelog lock....
2020-03-04T11:10:52.88+0200 SELECT LOCKED FROM public.databasechangeloglock WHERE ID=1
2020-03-04T11:10:52.88+0200 Waiting for changelog lock....
2020-03-04T11:10:54.00+0200 ERR 2020-03-04 09:10:54.010 UTC
2020-03-04T11:10:55.88+0200 [HEALTH/0] ERR Failed to make TCP connection to port 8080: connection refused
2020-03-04T11:10:55.88+0200 [CELL/0] ERR Failed after 1m0.626s: readiness health check never passed.
2020-03-04T11:10:55.89+0200 [CELL/SSHD/0] OUT Exit status 0
2020-03-04T11:10:55.89+0200 info [native] Initiating shutdown sequence for Java agent
2020-03-04T11:10:55.89+0200 info [] Connection Status (120 times 300s) : 0909
是否存在用于在一定时间后自动删除Liquibase DATABASECHANGELOGLOCK的配置，或者如果它早于5分钟或预定义的时间段，则在应用程序启动时将其删除.还是可以在Postgres开始寻找变更锁之前在App Start上以编程方式完成此操作.
Is there a configuration for removing Liquibase DATABASECHANGELOGLOCK automatically after a certain time or removing it on application start if it is older than let's say 5 mins or a predefined time period. Or can this be done programatically at App Start before Postgres starts looking for the change lock.
推荐答案
因此，我可以通过以下方法实现这一目标:
So I was able to achieve this via the following approach:
我们使用SpringLiquibase bean初始化LiquiBase.
We initialise LiquiBase using a SpringLiquibase bean.
在此bean中，在构造Liquibase实例之前，我调用了一种方法，该方法使用Statements向数据库查询锁，如果有任何超过5分钟的锁，我们将其删除.
Within this bean, before the Liquibase instance is constructed, I called a method which uses Statements to query the database for a lock, and if there are any locks older than 5 minutes, we delete them.
@Bean
public SpringLiquibase liquibase(DataSource dataSource) {
// Added a hook to check for locks before LiquiBase initialises.
removeDBLock(dataSource);
//
SpringLiquibase liquibase = new SpringLiquibase();
liquibase.setChangeLog(Constants.DDL_XML);
liquibase.setDataSource(dataSource);
return liquibase;
}
private void removeDBLock(DataSource dataSource) {
//Timestamp, currently set to 5 mins or older.
final Timestamp lastDBLockTime = new Timestamp(System.currentTimeMillis() - (5 * 60 * 1000));
final String query = format("DELETE FROM DATABASECHANGELOGLOCK WHERE LOCKED=true AND LOCKGRANTED<'%s'", lastDBLockTime.toString());
try (Statement stmt = dataSource.getConnection().createStatement()) {
int updateCount = stmt.executeUpdate(query);
if(updateCount>0){
log.error("Locks Removed Count: {} .",updateCount);
}
} catch (SQLException e) {
log.error("Error! Remove Change Lock threw and Exception. ",e);
}
}
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