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Background documentationProfile Parameters for the Enqueue Clients Locate this document in the navigation structure


Note Note

The following settings are only relevant for enqueue clients for Application Server ABAP.

End of the note.

If you want to use the standalone enqueue server, you have to set the following parameters in the profile files of the enqueue clients (application server instances):

enque/process_location = REMOTESA

enque/serverhost = <host name of the enqueue server>

enque/serverinst = <instance number of the enqueue server>

enque/deque_wait_answer = TRUE (note the use of upper and lower case here)

This parameter determines whether the dequeue (removal of locks) is done synchronously or asynchronously. The parameter can have the following values:

  • TRUE: Waits for response from the enqueue server (synchronous)

  • FALSE: Does not wait for response (asynchronous)

Establishing Connection to Standalone Enqueue Server

The following parameters should already have appropriate default values. If necessary though, you can change these values.

  • enque/con_timeout = 5000

    The parameter specifies the maximum time (in milliseconds) the client can block for when a connection is being set up. If the connection cannot be established, the client waits for one second and then retries. Parameter enque/con_retriesdetermines how often the attempts are repeated.

    Note Note

    If the standalone enqueue server is not available at any time, the process is blocked for this time. If the enqueue server still cannot be contacted once the timeout has expired, a "SYSTEM_FAILURE" exception is issued to the application, which may not be desirable. For this reason when you create these two parameters, you have to weigh up how long the work processes are allowed to be blocked for, and how much time the enqueue server and the HA software need for a failover.

    End of the note.

    Recommendation Recommendation

    enque/con_timeout should not be too large, so that the work processes can connect to the enqueue server as soon as it is available again. However, it should not be so small that the network is flooded with connect attempts during the time the enqueue server is not available.

    End of the recommendation.
  • enque/con_retries = 60

    After the specified number of retries, the caller (the application) reports an error.

    The entire wait time is therefore between

    1s* enque/con_retries and (1s + enque/con_timeout ms)  * enque/con_retries.

    Caution Caution

    This is only valid if enque/con_retries does not have the value 0. Value enque/con_retries = 0 means that the client attempts to establish the connection infinitely.

    End of the caution.

    Note Note

    If you do not set the value to 0, it should be larger than the typical time for an (A)SCS instance failover. This depends largely on your operating system and your cluster solution. If a failover can take longer, you should increase the value of these parameters.

    End of the note.

More Information

For further information about profile parameters refer to the sections below.

Profile Parameters for the Standalone Enqueue Server

Profile Parameters for the Enqueue Replication Server

The standard parameters used in the enqueue environment are described in the section Important Profile Parameters for the Lock Concept.