Help Center/ MapReduce Service/ User Guide/ MRS Cluster O&M/ MRS Cluster Alarm Handling Reference/ ALM-12190 Number of Knox Connections Exceeds the Threshold
Updated on 2024-09-23 GMT+08:00

ALM-12190 Number of Knox Connections Exceeds the Threshold

Alarm Description

The system periodically checks the number of connections to all Knox topologies. This alarm is generated when the number of connections to a topology exceeds the threshold (90% by default). This alarm is automatically cleared when the number of connections to a topology falls below the threshold.

This alarm applies to clusters of MRS 3.1.0 or later.

Alarm Attributes

Alarm ID

Alarm Severity

Auto Cleared

12190

Major

Yes

Alarm Parameters

Parameter

Description

Source

Specifies the cluster or system 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.

Topology

Specifies the Knox topology for which the alarm was generated.

Impact on the System

The topology may reach the upper limit of connections and fail to forward requests, adversely affecting the MRS functions.

Possible Causes

Hue or Manager is too frequently used, but the default maximum number of Knox connections is small.

Handling Procedure

  1. Log in to active and standby OMS nodes as user root, respectively.
  2. Add the following configuration to the gateway-site.xml file on the active and standby OMS nodes to increase the number of thread pools:

    vi /opt/knox/conf/gateway-site.xml

    <property>
    <name>gateway.httpclient.maxConnections</name>
    <value>64</value>
    </property>

  3. Log in to the active OMS node as user omm and run the following command to restart the Knox process:

    sh /opt/knox/bin/restart-knox.sh

  4. After 5 minutes, check whether the alarm is cleared.

    • If yes, no further action is required.
    • If no, go to 5.

  5. Contact O&M personnel to rectify the fault.

Alarm Clearance

This alarm is automatically cleared after the fault is rectified.

Related Information

None