Re: Flink parameter configuration does not take effect

Jason Lee Thu, 17 Jun 2021 04:18:13 -0700

Hi Robert,

Thank you for your enthusiastic answer

I have understood the current problem and look forward to a good solution and
optimization by the community. I will continue to pay attention to changes in
the community.

Best,
Jason

On 06/17/2021 15:45，Robert Metzger<rmetz...@apache.org> wrote：
Hi Jason,

I hope you don't mind that I brought back the conversation to the user@ mailing
list, so that others can benefit from the information as well.

Thanks a lot for sharing your use case. I personally believe that Flink should
support invocations like "flink run -m yarn-cluster xxx.FlinkStreamSQLDDLJob
flink-stream-sql-ddl-1.0.0.jar ./config.json". There is no fundamental reason
why this can not be supported.

The Javadoc about tableEnv.getConfig() mentions that the config is only about
the "runtime behavior":
https://github.com/apache/flink/blob/master/flink-table/flink-table-api-java/src/main/java/org/apache/flink/table/api/TableEnvironment.java#L1151

... but I see how this is not clearly defined.

As a short-term fix, I've proposed to clarify in the configuration table which
options are cluster vs job configurations:
https://issues.apache.org/jira/browse/FLINK-22257.

But in the long term, we certainly need to improve the user experience.

On Wed, Jun 16, 2021 at 3:31 PM Jason Lee <jasonlee1...@163.com> wrote:

Dear Robert,

For tasks running on the cluster, some parameter configurations are global, but
some parameter configurations need to be customized, such as some memory
settings of TaskManager. For tasks with different state sizes, we need to
configure different parameters. These parameters should not be configured in
flink-config.yaml. But for the current Flink, these parameters cannot be
configured through StreamExecutionEnvironment, and some parameters are not
effective if set through StreamTableEnvironment.

At the same time, Configuration is immutable after the task is started, which
is correct, but I think some global parameters should also be specified in
StreamExecutionEnvironment. At present, some parameters of checkpoint are also
set globally, but they can be set through "StreamExecutionEnvironment
.getCheckpointConfig().set()", then why can't the parameters of TaskManager's
memory be set in this way? I think that setting the global parameters by "flink
run -yD" is the same as setting by "StreamExecutionEnvironment". I am not sure
if I understand it correctly.

I agree with you. I think we need to specify in the configuration of the
official document that those parameters are best configured in
flink-config.yaml. Those parameters can be modified in
"StreamExecutionEnvironment", and those can only be passed through others
Modified in the way. I think the document will be clearer for users.

On 06/16/2021 21:04，Jason Lee<jasonlee1...@163.com> wrote：
Dear Robert,

Thanks for your answer

Our Flink SQL task is deployed through Per job.

We provide our users with a platform for developing Flink SQL tasks. We will
write the user's SQL code and configuration parameters into a Config.json file.
At the same time, we develop a Flink Jar task at the bottom to actually execute
the user's SQL through the command line. To perform this task, for example, the
following is our instruction to start a Flink SQL task: "flink run -m
yarn-cluster xxx.FlinkStreamSQLDDLJob flink-stream-sql-ddl-1.0.0.jar
./config.json". In order to facilitate the user's personalized configuration
parameters, we want to set user configuration parameters in the execution
environment of the FlinkStreamSQLDDLJob class that we have implemented, such as
the "taskmanager.memory.managed.fraction" parameter, but it is currently
impossible to configure through the Flink execution environment These
parameters, because they are not effective, can only be configured by flink run
-yD.

I think the configuration in the official document states that those parameters
cannot be set through
"StreamTableEnvironment.getConfig.getConfiguration().set()", but can only be
set through flink run -yD or configured in flink-conf.yaml. If the current
document does not explain it, it will not take effect if you use the
"StreamTableEnvironment.getConfig.getConfiguration().set()" method to set some
parameters. In order to increase the use of personalized configuration
parameters for users, I think these instructions can appear in the
Configuration of the official document.

Best,
Jason

On 06/16/2021 18:37，Robert Metzger<rmetz...@apache.org> wrote：
Hi Jason,

How are you deploying your Flink SQL tasks? (are you using per-job/application
clusters, or a session cluster? )

I agree that the configuration management is not optimal in Flink. By default,
I would recommend assuming that all configuration parameters are cluster
settings, which require a cluster restart. Very few options (mostly those
listed in the "Execution" section) are job settings, which can be set for each
job.

Would it help if the table of configuration options in the documentation would
tag the configuration option (with "Cluster" and "Job" option types?)?
Secondly, the API should probably only expose an immutable Configuration
object, if the configuration is effectively immutable. I believe the option to
set configuration on the (Stream)(Table)Environment is mostly there for local
execution of Flink.

2. I agree, the docs are incomplete here (probably another symptom of the fact
that the whole configuration management in Flink is not optimal). I see what I
can do to improve the situation.

3. Except for local execution (everything runs in one JVM), I don't think we'll
add support for this anytime soon. Some of the cluster configuration parameters
just have to be global (like memory management), as they apply to all jobs
executed on a cluster.

This ticket could be related to your problems:
https://issues.apache.org/jira/browse/FLINK-21065

Let us know how you are deploying your Flink jobs, this will shed some more
light on the discussion!

Best,
Robert

On Wed, Jun 16, 2021 at 4:27 AM Jason Lee <jasonlee1...@163.com> wrote:

Hi everyone,

When I was researching and using Flink recently, I found that the official
documentation on how to configure parameters is confusing, and when I set the
parameters in some ways, it does not take effect. mainly as follows:

we usually use a DDL Jar package to execute Flink SQL tasks, but we found that
some parameters are set by
StreamTableEnvironment.getConfig().getConfiguration().setXXX(key, value). These
parameters cannot take effect. For example, taskmanager.memory.managed.fraction
cannot take effect if the parameter is set in the above way (the Note in
TableConfig in the source code is as follows: Because options are read at
different point in time when performing operations, it is recommended to set
configuration options early after instantiating a table environment. ). And
StreamExecutionEnvironment.getConfiguration() is protected, which leads to some
parameters that cannot be set through the api. I feel that this is not
reasonable. Because sometimes, we want to configure different parameters for
different tasks in the form of Configuration.setxxx(key, value) in the api,
instead of just configuring parameters through flink run -yD or flink-conf.yaml.

In the Configuration module of the official document, the description and
default value of each parameter are introduced. There is no relevant
introduction about the parameter setting method in the official document
Configuration module. I think this is not friendly enough for users, especially
users who want to personalize some parameters. I feel that this method can be
described in the official document.

In summary, for some normal tasks we can use the default parameter
configuration, but for some tasks that require personalized configuration,
especially Flink SQL tasks, I have a few suggestions on the use of
configuration:

1. Regarding the api, I think that
StreamTableEnvironment.getConfig().getConfiguration().setXXX(key, value)
configures parameters in this way. It should be separately explained, which
parameters are not effective if configured in this way, otherwise, Some
parameters configured in this way will not take effect, which will cause
confusion for users.

2. In the official document, I think it is necessary to add instructions on how
to configure these parameters. For example, it can be configured not only in
flink-conf.yaml, but also in the running command through flink run -yD, or
whether there are other The parameters can be configured in the mode.

3. Questions about StreamExecutionEnvironment.getConfiguration() being
protected. Will the community develop in later versions? Is there any effective
way for users to set some parameters in the api and make them effective, such
as configuring the taskmanager.memory.managed.fraction parameter.

Regarding some of the above issues, and why the parameter setting will not take
effec. Maybe I did not describe it clearly enough, or because I did not
understand the problem clearly, I hope to get a reply and discuss from the
community.

Best,
Jason

Re: Flink parameter configuration does not take effect

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