:original_name: ALM-45637.html

.. _ALM-45637:

ALM-45637 FlinkServer Task Is Continuously Under Back Pressure
==============================================================

This section applies to MRS 3.1.2 or later.

Description
-----------

The system checks the back pressure duration of FlinkServer tasks based on the configured alarm checking interval. This alarm is generated when the back pressure duration of a FlinkServer task reaches the configured threshold. This alarm is cleared when the task back pressure is recovered or the job is successfully restarted.

Attribute
---------

======== ============== ==========
Alarm ID Alarm Severity Auto Clear
======== ============== ==========
45637    Minor          Yes
======== ============== ==========

Parameters
----------

=========== =======================================================
Name        Meaning
=========== =======================================================
Source      Specifies the cluster for which the alarm is generated.
ServiceName Specifies the service for which the alarm is generated.
JobName     Specifies the job for which the alarm is generated.
=========== =======================================================

Impact on the System
--------------------

This alarm has no impact on the system.

Possible Causes
---------------

You can view the causes in the specific logs.

Procedure
---------

#. Log in to Manager as a user who has the FlinkServer management permission.

#. Choose **Cluster** > **Services** > **Yarn** and click the link next to **ResourceManager WebUI** to go to the Yarn page.

#. Locate the failed job based on its name displayed in **Location**, search for and record the application ID of the failed job, and check whether the job logs are available on the Yarn page.


   .. figure:: /_static/images/en-us_image_0000001583127393.png
      :alt: **Figure 1** Application ID of a job

      **Figure 1** Application ID of a job

   If yes, go to :ref:`4 <alm-45637__en-us_topic_0000001150940918_li109051158191>`.

   If no, go to :ref:`6 <alm-45637__en-us_topic_0000001150940918_li5902415141913>`.

#. .. _alm-45637__en-us_topic_0000001150940918_li109051158191:

   Click the application ID of the failed job to go to the job page.

   a. Click **Logs** in the **Logs** column to view JobManager logs.


      .. figure:: /_static/images/en-us_image_0000001582807701.png
         :alt: **Figure 2** Clicking Logs

         **Figure 2** Clicking Logs

   b. Click the ID in the **Attempt ID** column and click **Logs** in the **Logs** column to view TaskManager logs.


      .. figure:: /_static/images/en-us_image_0000001583127389.png
         :alt: **Figure 3** Clicking the ID in the Attempt ID column

         **Figure 3** Clicking the ID in the Attempt ID column


      .. figure:: /_static/images/en-us_image_0000001532927426.png
         :alt: **Figure 4** Clicking Logs

         **Figure 4** Clicking Logs

      .. note::

         You can also log in to Manager as a user who has the FlinkServer management permission, choose **Cluster** > **Services** > **Flink**, click the link next to **Flink WebUI**. On the displayed Flink web UI, click **Job Management** and choose **More** > **Job Monitoring** in the **Operation** column to view the TaskManager logs.

#. View the logs of the failed job to rectify the fault, or contact the O&M personnel personnel and send the collected fault logs. No further action is required.

**If logs are unavailable on the Yarn page, download logs from HDFS.**

6. .. _alm-45637__en-us_topic_0000001150940918_li5902415141913:

   On Manager, choose **Cluster** > **Services** > **HDFS**, click the link next to **NameNode WebUI** to go to the HDFS page, select **Utilities** > **Browse the file system**, and download logs in the **/tmp/logs/**\ *User name*\ **/logs/**\ *Application ID of the failed job* directory.

7. View the logs of the failed job to rectify the fault, or contact the O&M personnel personnel and send the collected fault logs.

Alarm Clearing
--------------

This alarm is cleared when FlinkServer task back pressure is recovered or the job is successfully restarted.

Related Information
-------------------

None
