Improving Lifecycle Query Engine performance

As an administrator, you might need to address performance issues that are not related to any of the query service or Lifecycle Query Engine node configurations. In these situations, you can review and update several advanced properties.
Important: Use caution when changing any of the advanced properties. It is not common to change these settings, and changes might adversely affect the system performance.

Improving performance by specifying advanced properties

Procedure

  1. On the Lifecycle Query Engine Administration page, under Configuration, click Advanced Properties. By default, you see only a few of the properties.

    Screen capture of the Advanced Properties page with only a few properties listed.

    • Connection Timeout: The timeout value in seconds for the connection between Lifecycle Query Engine and the data source. The default is 60.
    • Socket Timeout: The timeout value in seconds between the establishment of a connection between Lifecycle Query Engine 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.
  2. To see a more comprehensive list of properties, click Show Internal. For more information about each property, see LQE Properties page in the Jazz.net wiki.
    Note: You can undo any changes that you make by clicking Restore Defaults.

Preventing query overload

As the administrator, you can help prevent query overload and exhausted 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, suspends new activity. Any activities that are currently running are completed and the JVM enters a garbage collection state to reclaim unused memory. You can control the amount of time for this suspension by changing the Suspend Timeout setting.

For long running or analytical queries, the Heap and Stack Suspension should be enabled. The Heap Usage Threshold, Maximum Pending Writebacks, and Suspend Timeout values can be adjusted as needed.

Procedure

  1. On the Lifecycle Query Engine Administration page navigation, under Configuration, click Advanced Properties and click Show Internal.
  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 dataset views that must be reached before incoming writes are suspended. Default is 200 stacked writeback views.
    • Suspend Timeout: The maximum amount of time that incoming transactions are suspended. Default is 90 seconds.
    • Heap Usage Threshold: The threshold value that the JVM heap must reach before incoming activities are suspended if the Heap Suspension Enabled is enabled. For example, if the Heap Suspension Enabled is checked, and the value in the Heap Usage Threshold is “0.85”, all incoming activities are suspended when the JVM heap utilization reaches 85% of the maximum heap space. 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. Default is off.
    • Stack Suspension Enabled: If enabled, LQE activities such as base and change log indexing are suspended when the Journal Writeback dataset stack views reaches the value that is specified in Maximum Pending Writebacks. Default is off.
  5. To enable the suspension of LQE activities when the Heap Usage Threshold value is exceeded, select the Heap Suspension Enabled check box.
  6. To enable the suspension of the Journal Writeback dataset stack views when the Maximum Pending Writebacks value is exceeded, select the Stack Suspension Enabled check box.
  7. Restart the LQE server.
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