Multiple db in spring boot Unable to acquire JDBC Connection

Question

I set up two connections in my application with different postgres and mssql databases the application works, but when there are many queries to the database, I get an error: org.springframework.dao.DataAccessResourceFailureException: Unable to acquire JDBC Connection; nested exception is org.hibernate.exception.JDBCConnectionException: Unable to acquire JDBC Connection

We increased the maximum pool size, but it did not help. The problem is that this error appeared some time after connecting the second database (mssql), the load on it is quite small, one hundred requests per day. But when we leave one database (postgresql), we do not observe errors with jdbc

spring.datasource.hikari.connection-timeout=20000
spring.datasource.hikari.minimum-idle=5
spring.datasource.hikari.maximum-pool-size=100

spring.datasource.url=
spring.datasource.username=
spring.datasource.password=
spring.datasource.driverClassName=org.postgresql.Driver

spring.datasource.second.url=
spring.datasource.second.username=
spring.datasource.second.password=
spring.datasource.second.driverClassName=
com.microsoft.sqlserver.jdbc.SQLServerDriver
---------------------------------------------------
import com.zaxxer.hikari.HikariDataSource;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.sql.DataSource;
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = "com.app.repository",
        entityManagerFactoryRef = "firstEntityManagerFactory"
        ,transactionManagerRef= "firstTransactionManager"
)
public class FirstDBConfig {
    @Bean
    @Primary
    @ConfigurationProperties("spring.datasource")
    public DataSourceProperties firstDataSourceProperties() {
        return new DataSourceProperties();
    }

    @Bean
    @Primary
    @ConfigurationProperties("spring.datasource.configuration")
    public DataSource firstDataSource() {
        return firstDataSourceProperties().initializeDataSourceBuilder()
                .type(HikariDataSource.class).build();
    }

    @Primary
    @Bean(name = "firstEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean firstEntityManagerFactory(EntityManagerFactoryBuilder builder) {
        return builder
                .dataSource(firstDataSource())
                .packages("com.app.models")
                .build();
    }

    @Primary
    @Bean
    public PlatformTransactionManager firstTransactionManager(
            final @Qualifier("firstEntityManagerFactory") LocalContainerEntityManagerFactoryBean firstEntityManagerFactory) {
        return new JpaTransactionManager(firstEntityManagerFactory.getObject());
    }
}
------------------------------------------------------------

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.transaction.PlatformTransactionManager;
import org.apache.commons.dbcp.BasicDataSource;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.sql.DataSource;

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = "com.app.repositorysecond",
        entityManagerFactoryRef = "secondEntityManagerFactory"
        ,transactionManagerRef= "secondTransactionManager"
)
@Slf4j
public class SecondDBConfig {
    @Bean
    @ConfigurationProperties("spring.datasource.second")
    public DataSourceProperties secondDataSourceProperties() {
        return new DataSourceProperties();
    }

    @Bean
    @ConfigurationProperties("spring.datasource.second.configuration")
    public DataSource secondDataSource() {
        return secondDataSourceProperties().initializeDataSourceBuilder()
                .type(BasicDataSource.class).build();
    }

    @Bean(name = "secondEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean secondEntityManagerFactory(
            EntityManagerFactoryBuilder builder) {
        return builder
                .dataSource(secondDataSource())
                .packages("com.app.modelssecond")
                .build();
    }

    @Bean
    public PlatformTransactionManager secondTransactionManager(
            final @Qualifier("secondEntityManagerFactory") LocalContainerEntityManagerFactoryBean secondEntityManagerFactory) {
        return new JpaTransactionManager(secondEntityManagerFactory.getObject());
    }
}