The database lock monitor is an online monitoring tool for detecting and analyzing database lock situations. A database lock situation is when several jobs compete for a lock on one (or more) rows of a physical file member with update or read stability intent. One job obtains the lock, the remaining jobs have to wait until this lock is released. In the context of a 3-tier SAP system, this means that the jobs competing for a lock are the database shadow jobs of the application servers (each work process with a database connection on an application server has one corresponding iSeries job on the database server: the shadow job). The rows of a physical file member are the records of an SAP database table (an SQL table is a physical file with one member).
To call the database lock monitor, call transaction DB4COCKPIT.
1. In the navigation frame, choose Performance ® Lock Monitor.
A list of all SAP application servers currently active is displayed.
2. To display the database shadow jobs for one or more application servers, choose the application servers you are interested in.
3. To display the record locks for a particular job, double-click the corresponding job.
The lock status indicates whether the job is waiting for the record lock to be released (lock status WAIT) or whether it is holding the record lock (lock status HELD).
Ў To display all jobs that are waiting for a particular record lock to be released (lock status WAIT) and the job actually holding the lock (lock status HELD), choose the record lock in question.
4. Provided the table is known to the ABAP Dictionary, you can display the content of the record currently under lock competition from both lists by selecting it and choosing Display Records.
5. You can display the iSeries job log for a selected job from both lists by choosing Display Job Log. If a job is a shadow job of an SAP work process, there is a message at the beginning of the job log with message ID CPF9898 detailing which SAP work process (that is, SAP-internal work process number as listed by transaction SM50) on which application server is connected to the database.