diagnostic.md

Diagnostic

Support for diagnostic and instrumentation is provided via Node.js Diagnostic Channel API.

Execution model for tracing channels

The presence of the result and error properties and the order of tracing channels events follows the current pseudo-code flow:

function operation(options, callback) {
  const channel = tracingChannel('plt:kafka:example')
  const context = { operationId: 0n, options }

  try {
    channel.start.publish(context)

    doSomethingAsync((error, result) => {
      if (error) {
        context.error = error
        channel.error.publish(context)
        channel.asyncStart.publish(context)
        callback(error)
        channel.asyncEnd.publish(context)

        return
      }

      context.result = result
      channel.asyncStart.publish(context)
      callback(error)
      channel.asyncEnd.publish(context)
    })

    channel.end.publish(context)
  } catch (error) {
    context.error = error
    channel.error.publish(context)
    channel.end.publish(context)
  }
}

Common properties

Each tracing channel publishes events with the following common properties:

Name	Type	Description
connection	Connection	The current connection. This is only used by the plt:kafka:connections:connects and plt:kafka:connections:api channels
connectionPool	ConnectionPool	The current connection pool. This is only used by the plt:kafka:connections:pools:gets channel.
client	Depends on the operation	The current client. It can be a Base, Admin, Producer or Consumer if appropriate.
operationId	bigint	The current operation ID. This is unique across all channels.
result	Depends on the operation	The result of the operation. This is only present in the asyncStart and asyncEnd events.
error	Error	The error thrown by the operation. This is only present in the error event.

Published channels

Name	Description
plt:kafka:instances	Notifies any creation of a Connection, ConnectionPool, Base, Admin, Producer, Consumer or MessagesStream. This channel will publish objects with the type and instance property.

Published tracing channels

Name	Target	Description
plt:kafka:connections:connects	Connection	Traces a connection attempt to a broker.
plt:kafka:connections:api	Connection	Traces a low level API request.
plt:kafka:connections:pools:gets	ConnectionPool	Traces a connection retrieval attempt from a connection pool.
plt:kafka:base:apis	Base	Traces a Base.listApis request.
plt:kafka:base:metadata	Base	Traces a Base.metadata request.
plt:kafka:admin:topics	Admin	Traces a Admin.createTopics or Admin.deleteTopics request.
plt:kafka:admin:groups	Admin	Traces a Admin.listGroups, Admin.describeGroups or Admin.deleteGroups request.
plt:kafka:producer:initIdempotent	Producer	Traces a Producer.initIdempotentProducer request.
plt:kafka:producer:sends	Producer	Traces a Producer.send request.
plt:kafka:consumer:group	Consumer	Traces a Consumer.findGroupCoordinator, Consumer.joinGroup or Consumer.leaveGroup requests.
plt:kafka:consumer:heartbeat	Consumer	Traces the Consumer heartbeat requests.
plt:kafka:consumer:receives	Consumer	Traces processing of every message.
plt:kafka:consumer:fetches	Consumer	Traces a Consumer.fetch request.
plt:kafka:consumer:consumes	Consumer	Traces a Consumer.consume request.
plt:kafka:consumer:commits	Consumer	Traces a Consumer.commit request.
plt:kafka:consumer:offsets	Consumer	Traces a Consumer.listOffsets or Consumer.listCommittedOffsets request.