Oracle Lock Waits Test

An Oracle database server provides data concurrency and integrity between transactions using locking mechanisms. The locking activity of a database server must be monitored carefully because an application holding a specific lock for a long time could cause a number of other transactions relying on the same lock to fail. The Oracle Lock Waits test identifies the sessions that are waiting for acquiring a lock.

Note:

This test will not report metrics for an Oracle 12c CDB server.

The measures made by this test are as follows:

 

Target of the test : An Oracle server

Agent deploying the test : An internal agent

Outputs of the test : One set of results for every SID monitored.

Configurable parameters for the test
  1. TEST PERIOD - How often should the test be executed
  2. Host – The host for which the test is to be configured
  3. Port - The port on which the server is listening
  4. User – In order to monitor an Oracle database server, a special database user account has to be created in every Oracle database instance that requires monitoring. A Click here hyperlink is available in the test configuration page, using which a new oracle database user can be created. Alternatively, you can manually create the special database user. When doing so, ensure that this user is vested with the select_catalog_role and create session privileges.

    The sample script we recommend for user creation (in Oracle database server versions before 12c) for eG monitoring is:

    create user oraeg identified by oraeg

    create role oratest;

    grant create session to oratest;

    grant select_catalog_role to oratest;

    grant oratest to oraeg;

    The sample script we recommend for user creation (in Oracle database server 12c) for eG monitoring is:

    alter session set container=<Oracle_service_name>;

    create user <user_name>identified by <user_password> container=current default tablespace <name_of_default_tablespace> temporary tablespace <name_of_temporary_tablespace>;

    Grant create session to <user_name>;                                

    Grant select_catalog_role to <user_name>;

    The name of this user has to be specified here.

  5. Password – Password of the specified database user

    This login information is required to query Oracle’s internal dynamic views, so as to fetch the current status / health of the various database components.

  6. Confirm password – Confirm the password by retyping it here.
  7. includelocks – In this text box, provide a comma-separated list of lock types that require monitoring. By default, ‘all’ will be displayed here, indicating that locks of all types will be monitored.
  8. excludelocks - Here, provide a comma-separated list of lock types that do not require monitoring. By default, MR, RT, TS, and KT will be displayed here.
  9. ISPASSIVE – If the value chosen is yes, then the Oracle server under consideration is a passive server in an Oracle cluster. No alerts will be generated if the server is not running. Measures will be reported as “Not applicable" by the agent if the server is not up.
  10. waittime - Specify the aggregate wait time in seconds for all the lock waits. The default is 10.
  11. DETAILED DIAGNOSIS – To make diagnosis more efficient and accurate, the eG Enterprise suite embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option.

    The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled:

    • The eG manager license should allow the detailed diagnosis capability
    • Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Lock waits:

Indicates the number of lock waits.

Number

A high number of consistent lock waits in conjunction with high average lock time for a requested lock type may mean that lock(s) on specific object(s) are not being released by session(s) or are being held for a long time causing other sessions to wait for their release. The detailed diagnosis of this measure, if enabled, provides the details of the lock waits such as the object, session etc.

Avg lock wait time:

Indicates the duration for which sessions were waiting for this lock.

Secs

An high average lock wait time may mean sessions are having to wait for a long time to acquire locks on objects. The detailed diagnosis of this measure, if enabled, can be used to view the details of the sessions waiting for this lock.