ALM-45338 Presto Worker4 Process GC Time Exceeds the Threshold

Alarm Description

The system collects the garbage collection (GC) time of the Presto worker4 process every 30 seconds. This alarm is generated when the GC time exceeds the threshold (exceeds 5 seconds for three consecutive times). This alarm is cleared when the GC time of the worker4 process is less than or equal to the threshold.

Alarm Attributes

Alarm ID	Alarm Severity	Auto Cleared
45338	Minor	Yes

Alarm Parameters

Parameter	Description
ServiceName	Specifies the service for which the alarm was generated.
RoleName	Specifies the role for which the alarm was generated.
HostName	Specifies the host for which the alarm was generated.
Trigger Condition	Specifies the threshold for triggering the alarm.

Impact on the System

If the GC time of the worker4 process is too long, the worker4 process performance will be adversely affected, and the worker4 process will even become unavailable.

Possible Causes

The heap memory of the worker4 process is overused or inappropriately allocated, causing frequent occurrence of the GC process.

Handling Procedure

Check the GC duration.

Log in to FusionInsight Manager and choose O&M > Alarm > Alarms. Locate the row that contains this alarm and view the IP address and role name of the instance in Location.
On FusionInsight Manager, choose Cluster, click the name of the desired cluster, and choose Services > Presto. On the page that is displayed, click the Instance tab and click the Worker4 instance for which the alarm is generated to access its dashboard. In the upper right corner of the Dashboard page, click the drop-down list icon and select Customize. On the Customize Statistics page, choose Cluster Status, select Presto Garbage Collection Time, and click OK to check whether the GC time is greater than 5 seconds.
- If yes, go to 3.
- If no, go to 6.
On FusionInsight Manager, choose Cluster, click the name of the desired cluster, and choose Services > Presto. On the page that is displayed, click Configurations and All Configurations, choose Worker4 > JVM, increase the value of Xmx in the JAVA_OPTS parameter, and click Save.
Return to the Dashboard page, click More, and select Restart Service to restart the service.
Check whether the alarm is cleared.
- If yes, no further action is required.
- If no, go to 6.

Collect fault information.

On FusionInsight Manager, choose O&M. In the navigation pane on the left, choose Log > Download.
Expand the Service drop-down list, and select Presto for the target cluster.
Click in the upper right corner, and set Start Date and End Date for log collection to 10 minutes ahead of and after the alarm generation time, respectively. Then, click Download.
Contact O&M personnel and provide the collected logs.