Apache Flink - Manipulating the state of an object in an evictor or trigger

[M Singh]

Hi:

Is it safe to manipulate the state of an object in the evictor or trigger ?  Are there any best practices/dos and don't on this ?

Thanks

[M Singh]

Just wanted to see if there is any advice on this question.  Thanks

On Sunday, July 14, 2019, 09:07:45 AM EDT, M Singh <[hidden email]> wrote:

Hi:

Is it safe to manipulate the state of an object in the evictor or trigger ?  Are there any best practices/dos and don't on this ?

Thanks

[taher koitawala-2]

As far as I know. It is completely safe

On Fri, Jul 19, 2019, 1:35 AM M Singh <[hidden email]> wrote:

Just wanted to see if there is any advice on this question.  Thanks

On Sunday, July 14, 2019, 09:07:45 AM EDT, M Singh <[hidden email]> wrote:

Hi:

Is it safe to manipulate the state of an object in the evictor or trigger ?  Are there any best practices/dos and don't on this ?

Thanks

[Biao Liu]

Hi,

I don't find any official document about it.

There are several state relevant methods in `TriggerContext`. I believe it's absolutely safe to use state in `Trigger` through `TriggerContext`.

Regarding to `Evictor`, there is no such methods in `EvictorContext`. After taking a glance on relevant codes, I guess it's OK for now. But I suggest do not manipulate state in `Evictor` until there is an official guarantee.

BTW, I'm just wondering why do you want to manipulate state in `Evictor`? If your requirement is reasonable, maybe we could support it officially.

M Singh <[hidden email]> 于2019年7月14日周日 下午9:07写道：

Hi:

Is it safe to manipulate the state of an object in the evictor or trigger ?  Are there any best practices/dos and don't on this ?

Thanks

[M Singh]

Biao:

I am asking this question, just to understand the impact and best practices around it.  The state I am referring to it the objects that are passed to evictor.

https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/operators/windows.html#evictors

void evictBefore(Iterable<TimestampedValue<T>> elements, int size, W window, EvictorContext evictorContext);

And you are right, I also don't see this in this information in the docs.  That is the reason I wanted to find out.

Thanks again for your time.

Mans

  

On Friday, July 19, 2019, 02:15:02 AM EDT, Biao Liu <[hidden email]> wrote:

Hi,

I don't find any official document about it.

There are several state relevant methods in `TriggerContext`. I believe it's absolutely safe to use state in `Trigger` through `TriggerContext`.

Regarding to `Evictor`, there is no such methods in `EvictorContext`. After taking a glance on relevant codes, I guess it's OK for now. But I suggest do not manipulate state in `Evictor` until there is an official guarantee.

BTW, I'm just wondering why do you want to manipulate state in `Evictor`? If your requirement is reasonable, maybe we could support it officially.

M Singh <[hidden email]> 于2019年7月14日周日 下午9:07写道：

Hi:

Is it safe to manipulate the state of an object in the evictor or trigger ?  Are there any best practices/dos and don't on this ?

Thanks