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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-8458) Add the switch for keeping both the old mode and the new credit-based mode
Date Thu, 01 Mar 2018 14:32:00 GMT

    [ https://issues.apache.org/jira/browse/FLINK-8458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16382064#comment-16382064
] 

ASF GitHub Bot commented on FLINK-8458:
---------------------------------------

Github user zhijiangW commented on a diff in the pull request:

    https://github.com/apache/flink/pull/5317#discussion_r171575083
  
    --- Diff: flink-core/src/main/java/org/apache/flink/configuration/TaskManagerOptions.java
---
    @@ -269,15 +269,21 @@
     	public static final ConfigOption<Integer> NETWORK_BUFFERS_PER_CHANNEL =
     			key("taskmanager.network.memory.buffers-per-channel")
     			.defaultValue(2)
    -			.withDescription("Number of network buffers to use for each outgoing/incoming channel
(subpartition/input channel).");
    +			.withDescription("Number of network buffers to use for each outgoing/incoming channel
(subpartition/input channel)." +
    +				"In credit-based flow control mode, this indicates how many credits are exclusive
in each input channel. It should be" +
    +				" configured at least 2 for good performance. 1 buffer is for receiving in-flight
data in the subpartition and 1 buffer is" +
    +				" for parallel serialization.");
     
     	/**
     	 * Number of extra network buffers to use for each outgoing/incoming gate (result partition/input
gate).
     	 */
     	public static final ConfigOption<Integer> NETWORK_EXTRA_BUFFERS_PER_GATE =
     			key("taskmanager.network.memory.floating-buffers-per-gate")
     			.defaultValue(8)
    -			.withDescription("Number of extra network buffers to use for each outgoing/incoming
gate (result partition/input gate).");
    +			.withDescription("Number of extra network buffers to use for each outgoing/incoming
gate (result partition/input gate)." +
    +				" In credit-based flow control mode, this indicates how many floating credits are
shared among all the input channels." +
    +				" The floating buffers are distributed based on backlog (real-time output buffers
in the subpartition) feedback, and can" +
    +				" help relieve back-pressure caused by unbalanced data distribution among the subpartitions.");
    --- End diff --
    
    Yeah, I already added it.


> Add the switch for keeping both the old mode and the new credit-based mode
> --------------------------------------------------------------------------
>
>                 Key: FLINK-8458
>                 URL: https://issues.apache.org/jira/browse/FLINK-8458
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Network
>            Reporter: zhijiang
>            Assignee: zhijiang
>            Priority: Major
>             Fix For: 1.5.0
>
>
> After the whole feature of credit-based flow control is done, we should add a config
parameter to switch on/off the new credit-based mode. To do so, we can roll back to the old
network mode for any expected risks.
> The parameter is defined as {{taskmanager.network.credit-based-flow-control.enabled}} and
the default value is true. This switch may be removed after next release.



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