ALM-45587 IoTDBServer GC Duration Exceeds the Threshold

Alarm Description

The system checks the GC duration of the IoTDBServer process every 60 seconds. This alarm is generated when the GC duration exceeds the threshold for three consecutive times. You can choose O&M > Alarm > Threshold Configuration > Name of the desired cluster > IoTDB > GC > Total GC duration of IoTDBServer process (IoTDBServer) to change the threshold. This alarm is cleared when the GC duration is less than the threshold.

Alarm Attributes

Alarm Parameters

Impact on the System

A long GC duration of the IoTDBServer process may interrupt the services.

Possible Causes

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

Handling Procedure

Check the GC duration.

1. Log in to FusionInsight Manager and choose O&M. In the navigation pane on the left, choose Alarm > Alarms. On the page that is displayed, locate the row containing the alarm whose Alarm ID is 45587, view the role name in Location, and check the instance IP address.
2. Choose Cluster > Name of the desired cluster > Service > IoTDB > Instance. Click the IoTDBServer for which the alarm is generated to go to Dashboard. Click the drop-down list in the upper right corner of the chart area and choose Customize > GC. In the dialog box that is displayed, select Garbage Collection (GC) Time of IoTDBServer, and click OK. Check whether the GC time of the IoTDBServer process is greater than 12 seconds.
   • If yes, go to 3.
   • If no, go to 5.

3. Choose Cluster > Name of the desired cluster > Service > IoTDB > Configuration, click All Configurations, choose IoTDBServer > System, and increase the value of -Xmx in the GC_OPTS parameter.
   

   • The default value of -Xmx is 2G.
   • If this alarm is occasionally generated, increase the value by 0.5 times. If this alarm is frequently generated, double the value.
   • In the case of large service volume and high service concurrency, you are advised to add instances.

4. Check whether the alarm is cleared.
   • If yes, no further action is required.
   • If no, go to 5.

Collect the fault information.

5. On FusionInsight Manager, choose O&M. In the navigation pane on the left, choose Log > Download.
6. Expand the Service drop-down list, select IoTDB for the target cluster, and click OK.
7. Click the edit icon in the upper right corner, and set Start Date and End Date for log collection to 30 minutes ahead of and after the alarm generation time, respectively. Then, click Download.
8. Contact O&M engineers and provide the collected logs.

Alarm Clearance

This alarm is automatically cleared after the fault is rectified.

Related Information

None.