SpringBoot应用程序引发异常

Unable to acquire JDBC Connection; nested exception is org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection

在对API的若干请求之后

public Response getChainObjectDepartments(@RequestBody List<UUID> ids) {
  val ud = QUserDepartmentPlain.userDepartmentPlain;
  val d = QDepartmentPlain.departmentPlain;
  val result = jpaQueryFactory.select(d).from(d).join(ud).on(ud.departmentId.eq(d.id)).where(ud.userId.in(ids)).transform(
      groupBy(ud.userId).as(GroupBy.list(d))
  );
  return Response.ok(result);
}

我使用PostgreSQL和pgAdmin显示了会话的最后一个查询是由这个QueryDSL查询生成的：

select
        userdepart1_."user_id" as col_0_0_,
        department0_."id" as col_1_0_,
        department0_."id" as id1_29_,
        department0_."charge_leader_id" as charge_11_29_,
        department0_."dingtalk_id" as dingtalk2_29_,
        department0_."is_audit" as is_audi12_29_,
        department0_."is_enable" as is_enabl3_29_,
        department0_."name" as name4_29_,
        department0_."parent_id" as parent_i5_29_,
        department0_."remark" as remark6_29_,
        department0_."sort" as sort7_29_,
        department0_."tz_create" as tz_creat8_29_,
        department0_."tz_retire" as tz_retir9_29_,
        department0_."tz_update" as tz_upda10_29_
    from
        "organization"."department" department0_
    inner join
        "organization"."rel_user_department" userdepart1_
            on (
                userdepart1_."department_id"=department0_."id"
            )
    where
        userdepart1_."user_id" in (
            ? , ? , ? , ? , ? , ? , ? , ? , ? , ? , ? , ?
        )

当所有会话填充此查询时，应用程序开始抛出异常Unable to acquire JDBC Connection
最后，我通过在函数中添加@Transactional来解决这个问题（一般情况下，只有选择查询时，我不会在函数中添加@Transactional），但我仍然不知道这个QueryDSL查询有什么问题，为什么它必须有@Transactional。