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Fan-out / Fan-in is slow due to internal overhead #81

johnvarney opened this Issue Oct 29, 2017 · 5 comments


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johnvarney commented Oct 29, 2017

I am running a test based on the fan-in fan-out sample using a 1600 item array of 3 or 4 character strings.
The activity function just returns the string that was passed in as the input, taking between 0 and 94 ms.
There appears to be a huge amount of overhead as the orchestration function replays many times and it all takes about 180 to 240 seconds to complete.
I can see the history in the Azure storage account when I run it locally for testing but do not see the history when it is run in Azure.
I was expecting that completion would take a small multiple of the individual activity function time as they would be spawned very quickly and would be working in parallel.


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cgillum commented Oct 30, 2017

Thanks for opening this issue. I suspect the bottleneck isn't so much the parallelism, but the "fan-in" part which is single-threaded and currently involves a large amount of storage I/O.

Just for context, we haven't done any performance optimization yet. I suspect the thing that's killing perf in this specific scenario is the fact that we're re-fetching the instance history every time the orchestrator receives a batch of response messages. Some internal caching could really help us here because there is a ton of Azure Storage I/O that we're doing unnecessarily (we wanted to focus on correctness of behavior before doing perf work).

I've opened a separate issue to track the performance work I mentioned: #82. I'll keep this issue open as well to track making sure we improve your specific scenario.

@cgillum cgillum self-assigned this Oct 30, 2017

@cgillum cgillum changed the title from Fan-in fan-out test to Fan-out / Fan-in is slow due to internal overhead Oct 30, 2017


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NTTLuke commented Feb 26, 2018

Hi @cgillum,
I have the same issue (#92) working with Fan-out/Fan-in pattern.
I saw it has been closed by referring to this.
Any news ?
Thank you


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cgillum commented Feb 26, 2018

Nothing to share yet. Things have been a little slow on this front but will be picking up again very soon. The main point of contention for this work item is deciding whether to do a partial tactical performance fix or do a larger, longer-term performance boost on the Durable Task Framework itself. Stay tuned. This will definitely be addressed for GA.


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andreujuanc commented Apr 12, 2018

I would prefer a long-term solution for GA.

We are dealing with beta anyway, it's understandable.


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cgillum commented May 1, 2018

A fix has been made which will vastly improve performance in the next release. See this PR: #289

@cgillum cgillum closed this May 1, 2018

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