idleTimeMsPerSecond on Flink 1.9?

[Lakshmi Gururaja Rao <lr...@splunk.com>]

Hi

I'm trying to understand the implementation of idleTimeMsPerSecond.
Specifically what I'm trying to do is, adapt this metric to be used with
Flink 1.9 (for a fork).

I tried an approach similar to this PR
<https://github.com/apache/flink/pull/11564/files> and measuring the time
to request a new buffer is easy to adapt but I've found that there's a
difference in the way the mailbox loop runs in 1.9 vs. 1.12.1 and I end up
with under-reported values (for example a sink getting no data, reports
idleTimeMsPerSecond as 0 always which doesn't seem right).

I see that the threading model in StreamTask has changed significantly
after 1.9. Specifically, I think in Flink 1.9 there's no blocking Mailbox
loop as in the later versions (example
<https://github.com/apache/flink/blob/release-1.12.1/flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/tasks/mailbox/MailboxProcessor.java#L310>)
which is where the idle time is measured..

Maybe I'm missing something, but I guess I can't directly use the same
approach to measure idle time in 1.9? If so, I guess an alternative (more
expensive) approach may be to measure it when the task thread processes
records (like somewhere in this block
<https://github.com/apache/flink/blob/release-1.9.3/flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/io/StreamOneInputProcessor.java#L133>)
but I'm not sure if that would be the right/efficient thing to do..

Any suggestions on how to accurately measure task idle time in Flink 1.9?

--
Lakshmi

Re: idleTimeMsPerSecond on Flink 1.9?

[Till Rohrmann <tr...@apache.org>]

Hi Lakshmi,

as you have said the StreamTask code base has evolved quite a bit between
Flink 1.9 and Flink 1.12. With the mailbox model it now works quite
differently. Moreover, the community no longer actively maintains versions
< 1.11. Hence, if possible I would recommend you to upgrade to one of the
latest Flink versions if this is possible. That way you don't have to
implement these features yourself.

Cheers,
Till

On Mon, Mar 8, 2021 at 7:08 PM Lakshmi Gururaja Rao <lr...@splunk.com> wrote:

> Hi
>
> I'm trying to understand the implementation of idleTimeMsPerSecond.
> Specifically what I'm trying to do is, adapt this metric to be used with
> Flink 1.9 (for a fork).
>
> I tried an approach similar to this PR
> <https://github.com/apache/flink/pull/11564/files> and measuring the time
> to request a new buffer is easy to adapt but I've found that there's a
> difference in the way the mailbox loop runs in 1.9 vs. 1.12.1 and I end up
> with under-reported values (for example a sink getting no data, reports
> idleTimeMsPerSecond as 0 always which doesn't seem right).
>
> I see that the threading model in StreamTask has changed significantly
> after 1.9. Specifically, I think in Flink 1.9 there's no blocking Mailbox
> loop as in the later versions (example
> <https://github.com/apache/flink/blob/release-1.12.1/flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/tasks/mailbox/MailboxProcessor.java#L310>)
> which is where the idle time is measured..
>
> Maybe I'm missing something, but I guess I can't directly use the same
> approach to measure idle time in 1.9? If so, I guess an alternative (more
> expensive) approach may be to measure it when the task thread processes
> records (like somewhere in this block
> <https://github.com/apache/flink/blob/release-1.9.3/flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/io/StreamOneInputProcessor.java#L133>)
> but I'm not sure if that would be the right/efficient thing to do..
>
> Any suggestions on how to accurately measure task idle time in Flink 1.9?
>
> --
> Lakshmi
>