Monitoring Lifecycle Query Engine performance
When you log on to Lifecycle Query Engine (LQE), you can quickly assess the overall status by viewing information in various widgets on the home page. You can view the high-level status of data sources, nodes, the query service, and backups. If issues need to be addressed, such as errors with data sources, you can click to see the details and take the appropriate actions.
Monitoring the health of your LQE environment
About this task
To see the status of a particular LQE node, on the home page, at
click Health Overview under the node name in the Health
Monitoring widget.You can see details about the system memory and processor, and how the node is performing against the defined thresholds. These thresholds are defined on the Query Service configuration page that you can access by clicking the Edit query service configuration link in the Query Service widget.You can also define the thresholds for specific nodes on the LQE nodes page in the administration section at https:<host_name>:<port>/lqe/web/admin/nodes.
- To filter the content of the indexing and activity feeds, click Show filtering options in the Recent Indexer Activity widget on the home page, and select items in the lists.
Examining the status of nodes
To view a high-level summary of the health of the system, in the Health
Monitoring page navigation, click Overview.
To view detailed information for a specific node, go to the Performance
page, and choose the node from the list.
The following types of information are displayed in graphs or as lists:To view details about how the LQE node is performing over a period, select the date and time. In each section, the charts are updated to reflect what you selected.
Tip: You can show or hide individual lines in the charts by clicking the corresponding item in the legend.
- Memory consumption
- CPU consumption
- Query and indexing summary
- Index size
To monitor the performance on a specific partition, go to the Partition
The following types of information are displayed in graphs or as lists:
- Partition I/O operations
- Partition I/O operation time
- Partition size
- Query summary
Monitoring indexing activity statistics
On the Health Monitoring page, click Statistics in
the menu, and go to the properties under Dataset Statistics.
- Active Transactions: The number of active readers and writers, providing a view of activities of the index: queries, base logs, change logs, and so on.
- Completed Transactions: The number of completed transactions, including Read-transactions, Write-transactions, and aborted transactions.
- Journal Writebacks: A journal is a Jena TDB write-ahead log. This field
displays the number of transactions in the journal that are pending or have been written to the
backing index. You should monitor the number of pending and completed journal writebacks:
- Under normal conditions, there should be a low number of pending journal writebacks as the journal writebacks move from a pending state to a completed state.
- When the number of pending journal writebacks starts to increase and does not decrease over time, there is potential for heap space issues if this condition continues unabated.
- Suspensions: The number of suspensions that are pending or completed,
that timed out, or showed errors because the JVM heap space reached a threshold (The heap usage
threshold is set in advanced properties.). This situation causes the suspension of incoming
transaction activities.To address this problem, you can use the dataset suspension feature in Lifecycle Query Engine (LQE). A dataset suspension does the following tasks:
The following LQE advanced properties control dataset suspension:
- Blocks all new read and write operations to the dataset
- Waits for existing read operations to complete
- Attempts to flush journal writebacks to the index
- Heap Suspension Enabled: Initiates dataset suspension when a heap threshold is exceeded. This property is disabled by default.
- Heap Usage Threshold: Percentage of heap that is used to trigger suspension. The default is 85%.
- Stack Suspension Enabled: After a commit, initiates dataset suspension if the number of pending journal writes exceeds the maximum pending writebacks threshold. Starting in version 7.0.1, this property is enabled by default.
- Maximum Pending Writebacks: The threshold of pending writebacks when stack suspension takes place.
- Suspend Timeout: The number of seconds to wait for read operations to complete before attempting a journal flush. This value must be greater than the total of query timeout and rogue query timeout. For example, if the default query timeout is 600 seconds and default rogue timeout is 180 seconds, this value must be greater than 780 seconds.
- Overloads: The number of times an overload condition was encountered. An
overload can occur in the following situations:
- When the JVM garbage collection process starts because the heap usage threshold was reached and, after garbage collection, the JVM heap still exceeds the heap usage threshold.
- When the maximum value of pending writebacks is exceeded and, after stack suspension, the maximum value of pending writebacks is still exceeded.
- Running or Completed Queries: The number of queries that are running or completed. You should watch the number of running queries over time to determine whether they might potentially lock index writes if the queries don't finish or are not timed out properly.
To view currently running queries, go to Running Queries. All queries should end normally or
by timing out; however, in Apache Jena, some queries might become rogue.
, and click For information about how to handle rogue queries, see Preventing Out-of-memory errors in Lifecycle Query Engine.