Improving Lifecycle Query Engine performance

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As an administrator, you might need to address performance issues that aren’t related to any of the query service or Lifecycle Query Engine (LQE) node configurations. In these situations, you can review and update several advanced properties.

Important: Use caution when changing any of the advanced properties. It’s not common to change these settings, and changes might adversely affect the system performance.

Improving performance by specifying advanced properties

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Procedure

  1. On the LQE Administration page, under Configuration, click Advanced Properties.
    By default, you see only a few of the properties.
    Screen capture of the advanced properties page
    • Connection Timeout: The timeout value in seconds for the connection between LQE and the data source. The default is 60.
    • Socket Timeout: The timeout value in seconds between the establishment of a connection between LQE and the data source, and the receipt of any data from that source. The default is 60.
    • Reload Log Properties: Logging functions in the log4j.properties file that are used for debugging. The logging functions are disabled by default. You can edit this properties file to enable the logging functions and then reload the file to begin logging.
    If you modify a property setting, the change might be Dynamic, which means it takes effect immediately. Restartindicates that you must restart the nodes to apply a change.

    You can download all LQE log files from this page. Click the Download button. The settings in the log4j.properties file determine what log files you get.

  2. To see a more comprehensive list of properties, click Show Internal.
    For more information about each property, see LQE Properties on the Jazz®.net wiki.
    Note: You can undo any changes that you make by clicking Restore Defaults.

Preventing query overload

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As administrator, you can help prevent query overload and exhausted Java virtual machine (JVM) heap space in Lifecycle Query Engine by suspending new Read-transactions and Write-transactions to the index.

When heap suspension is enabled, LQE monitors the JVM heap space utilization and, when the threshold (Heap Usage Threshold) is exceeded, LQE suspends new activity. Any running activities are completed, and the JVM enters a garbage collection state to reclaim unused memory. You can control the amount of time that is allocated for this suspension by changing the Suspend Timeout setting.

For long running or analytical queries, the Heap and Stack Suspension should be enabled. As needed, you can adjust the values for Heap Usage Threshold, Maximum Pending Writebacks, and Suspend Timeout.

Procedure

  1. On the LQE administration page, in the menu under Configuration, click Advanced Properties.
  2. To see a more comprehensive list of properties, click Show Internal.
  3. In the Internal Properties Configuration section, click Edit.
  4. In the Query section, scroll down to the following properties:
    • Maximum Pending Writebacks: The number of stacked journal writeback data set views that must be reached before incoming Write-operations are suspended. The default is 200 stacked writeback views.
    • Suspend Timeout: The maximum amount of time that incoming transactions are suspended. The default is 90 seconds.
    • Heap Usage Threshold: The threshold value that the JVM heap must reach before incoming activities are suspended if Heap Suspension Enabled is enabled. For example, if Heap Suspension Enabled is selected, and the Heap Usage Threshold value is 0.85, all incoming activities are suspended when the JVM heap utilization reaches 85 percent of the maximum heap space. The default is 0.85.
    • Heap Suspension Enabled: If enabled, LQE activities such as incoming queries are suspended when the heap space size reaches the percentage value that is specified in Heap Usage Threshold. By default, it’s off.
    • Stack Suspension Enabled: If enabled, LQE activities such as base and change log indexing are suspended when the journal writeback data set stack views reach the value that is specified in Maximum Pending Writebacks. By default, it’s off.
  5. To suspend LQE activities when the Heap Usage Threshold value is exceeded, select the Heap Suspension Enabled check box.
  6. To suspend the journal writeback data set stack views when the Maximum Pending Writebacks value is exceeded, select the Stack Suspension Enabled check box.
  7. Restart the LQE server.