ORA-00018: maximum number of sessions exceeded解决方法
应用跑了一段时间后，偶尔发生System Runtime Error:
Could not open JDBC Connection for transaction; nested exception is java.sql.SQLException: ORA-00018: maximum number of sessions exceeded 错误，ORA-00018其实是oracle session及process占满的原因，解决方法：
1、加大process ,session数配置，用dba身份登陆oracle
     A、find session hight water

         SQL>  select  *  from v$license;--查看session占用情况

     B、Current  parameter process and session

         SQL> show parameter process

         NAME                                 TYPE        VALUEITPUB
         ------------------------------------ ----------- ------------         ------------------
         aq_tm_processes                      integer     0
         db_writer_processes                  integer     1
         job_queue_processes                  integer     0
         log_archive_max_processes            integer     2
         processes                            integer     150
     C、SQL> show parameter session

         NAME                                 TYPE        VALUE
         ------------------------------------ ----------- ------------         ------------------
         java_max_sessionspace_size           integer     0
         java_soft_sessionspace_limit         integer     0
         license_max_sessions                 integer     0ITPUB
         license_sessions_warning             integer     0ITPUB
         logmnr_max_persistent_sessions       integer     1
         mts_sessions                         integer     0
   &n