Help Center/ MapReduce Service/ User Guide/ MRS Cluster O&M/ MRS Cluster Alarm Handling Reference/ ALM-45284 UserSync Garbage Collection (GC) Time Exceeds the Threshold
Updated on 2024-09-23 GMT+08:00
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ALM-45284 UserSync Garbage Collection (GC) Time Exceeds the Threshold

Alarm Description

The system checks the GC duration of the UserSync process every 60 seconds. This alarm is generated when the GC duration of the UserSync process exceeds the threshold (12 seconds by default) for five consecutive times. This alarm is cleared when the GC duration is less than the threshold.

Alarm Attributes

Alarm ID

Alarm Severity

Auto Cleared

45284

Major

Yes

Alarm Parameters

Parameter

Description

Source

Specifies the cluster for which the alarm was generated.

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

Threshold for triggering the alarm.

Impact on the System

UserSync responds slowly.

Possible Causes

The heap memory of the UserSync instance is overused or the heap memory is inappropriately allocated. As a result, GCs occur frequently.

Handling Procedure

Check the GC time.

  1. On FusionInsight Manager, choose O&M > Alarm > Alarms > ALM-45284 UserSync Garbage Collection (GC) Time Exceeds the Threshold. Check the location information of the alarm and view the host name of the instance for which the alarm is generated.
  2. On FusionInsight Manager, choose Cluster > Services > Ranger > Instance. Select the role corresponding to the host name of the instance for which the alarm is generated and click the drop-down list in the upper right corner of the chart area. Choose Customize > GC > UserSync GC Duration. Click OK.

    Figure 1 UserSync GC Duration

  3. Check whether the GC duration of the UserSync process collected every minute exceeds the threshold (12 seconds by default).

    • If yes, go to 4.
    • If no, go to 6.

  4. On FusionInsight Manager, choose Cluster > Services > Ranger > Instance > UserSync > Instance Configuration. Click All Configurations, and choose UserSync > System. Increase the value of -Xmx in the GC_OPTS parameter based on the site requirements and save the configuration.

    If this alarm is generated, the heap memory configured for UserSync cannot meet the heap memory required by the UserSync process. You are advised to change the value of GC_OPTS to the twice that of the heap memory used by UserSync. You can change the value based on the actual service scenario. For details about how to check the UserSync heap memory usage, see 2.

  5. Restart the affected services or instances and check whether the alarm is cleared.

    • If yes, no further action is required.
    • If no, go to 6.

      During the service restart, the service is interrupted. During the instance restart, the instance is unavailable, and the task on that instance fails to be executed.

Collect the fault information.

  1. On FusionInsight Manager, choose O&M > Log > Download.
  2. Expand the Service drop-down list, and select Ranger for the target cluster.
  3. 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.
  4. Contact O&M personnel and provide the collected logs.

Alarm Clearance

After the fault that triggers the alarm is rectified, the alarm is automatically cleared.

Related Information

None