The latest version for DAS is WSO2 Data Analytics Server 3.1.0. View documentation for the latest release.
WSO2 Data Analytics Server is succeeded by WSO2 Stream Processor. To view the latest documentation for WSO2 SP, see WSO2 Stream Processor Documentation.

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The possible exceptions relating to event receivers that may occur are as follows:

Queue full exception

Sample Error log
event for endpoint group [ ( Receiver URL : tcp://das-1.-prod.local:7611, Authentication URL : ssl://das-1.-prod.local:7711),( Receiver URL : tcp://das-2.-prod.local:7611, Authentication URL : ssl://das-2.-prod.local:7711) ], 139882 events dropped so far. {org.wso2.carbon.databridge.agent.DataPublisher}
TID: [-1] [] [2017-05-23 00:05:53,708] ERROR
{org.wso2.carbon.databridge.agent.endpoint.DataEndpoint} - Unable to send events to the endpoint. {org.wso2.carbon.databridge.agent.endpoint.DataEndpoint}
org.wso2.carbon.databridge.agent.exception.DataEndpointException: Cannot send Events
OccurrenceThis occurs on the client side when using the WSO2Event event receiver.
Possible reasons
  • The TCP connection between the databridge client and the DAS server may not be established.
  • The DAS server may be unresponsive because it is unable to handle the event load due to resource constraints, or because it is not tuned properly. The insufficiently allocated resources may include CPU, memory, disk space, network bandwiidth, DB capacity etc.
  • The database may be unable to receive the data fast enough, resulting in it being a bottleneck. This can happen if the database is an RDBMS database such as MySQL, due to limited capacity.
Troubleshooting options

To check the TCP connection, enable event tracing and event logs, and make sure that one or more events are received by WSO2 DAS.

To log all the events received via WSO2Event event receivers deployed in DAS, add the following logger to the <DAS_HOME>/repository/conf/log4j.properties file.
org.wso2.carbon.event.input.adapter.wso2event.internal.ds.WSO2EventAdapterServiceDS=DEBUG 

For more information, see the following topics:

Recommended action
  • To check the database persistence and database receiver rate, the following properties can be set when the DAS server is started (e.g., ./bin/wso2server.sh -DprofileReceiver=true):
    • -DprofileReceiver=true :This enables you to check the throughput per receiver. This creates the receiver-perf.txt file in the DAS_HOME. The throughput is calculated and published in this file for every 100000 events.
    • -DreceiverStatsCutoff=2000 : This specifies the number of events for which the  receiver-perf.txt  file generated via the  -DprofileReceiver  property is updated. e.g.,  If 2000 is specified, new statistics are inserted into the  r eceiver-perf.txt  file for every batch of 2000 events received via the databridge agent. The default value is 100000 events.
    • -DprofilePersistence=true : This allows you to check the throughput at the persistence (i.e., Data Access Layer) level. This creates the persistence-perf.txt file in the DAS_HOME .
    • -DpersistenceStatsCutoff=1000 : This property specifies the number of events for which the persistence-perf.txt file generated via the -DprofilePersistence property is updated. If this property is not set, 100000 is considered the default number.
  • NoSQL databases such as HBase are recommended for high throughput environments to avoid this exception.


Dropping incorrectly formatted events

Exception
wso2carbon.log:114:TID: [-1234] [] [2017-03-31 00:00:01,155] ERROR {org.wso2.carbon.databridge.core.internal.queue.QueueWorker} -  Dropping wrongly formatted event sent for -1234 {org.wso2.carbon.databridge.core.internal.queue.QueueWorker}
wso2carbon.log-115-org.wso2.carbon.databridge.core.exception.EventConversionException: Error when converting 1 of event bundle with events 6
wso2carbon.log-116-	at org.wso2.carbon.databridge.receiver.thrift.converter.ThriftEventConverter.createEventList(ThriftEventConverter.java:181)
OccurrenceThis may occur when you publish events to WSO2 DAS before the server startup of DAS is completed.
Possible reasons
  • If this exception occurs for events that were sent before the DAS server start-up, it can be due to a delay in the deployment of one or more artifacts deployed via CAR files.
  • If this exception occurs for events that are sent after the DAS server start-up, it is because the relevant event stream is not defined or deployed in WSO2 DAS. For more information about event streams, see Understanding Event Streams and Event Tables.
Troubleshooting options
  • Check whether the required event stream is included in the list of event streams displayed in the Available Event Streams page. To access this page, access the DAS Management Console, go to the Main tab and click Streams in the left navigator. For more information, see Understanding Event Streams and Event Tables .
  • Go to the <DAS_HOME>/repository/deployment/server/eventstreams directory and check whether the required event stream definition exists.
  • Check the startup log to see whether the required event stream is successfully deployed as shown in the following example.
     
Recommended action
  • If the stream is not deployed, redeploy the stream or the car file that contains it. For more information, see Packaging Artifacts s a C-App Archive.
  • Define the required event stream. For more information, see Understanding Event Streams and Event Tables.
  • To prevent the DAS server from receiving events before event streams are deployed, add the following property to the <dataReceiver name="Thrift"> configuration in the <DAS_SERVER>/repository/conf/data-bridge/data-bridge-config.xml file.
    <config name="waitingTimeInMilliSeconds">{waitingTime}</config>

    You need to restart the DAS server after adding this configuration for it to be effective.


Enabling debugging logs allow you to further monitor event receivers and prevent exceptions. For more information, see Debugging Event Receivers.



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