MFIter::allow_multiple_mfiters' failed

[wuxf99]

0::Assertion `depth == 1 || MFIter::allow_multiple_mfiters' failed, file "/home/wuxf/amrex/Src/Base/AMReX_MFIter.cpp", line 254, Msg: "Nested or multiple active MFIters is not supported by default. This can be changed by calling MFIter::allowMultipleMFIters(true)". !!! SIGABRT

Any comments about how to fix it?

[WeiqunZhang]

This is usually a bug in the user's code. The assertion is there to prevent common bugs like below

for (MFIter mfi(...) ....) {
     for (MFIter ....) {}; // or a function that contains MFIter loop
}

The error message has already provided a way to get around it if the pattern above is not a bug for you.

[wuxf99]

I see, thanks. I don't think my code has a bug. This assertion caused the crash of my code. When I added MFIter::allowMultipleMFIters(true) before the assertion, it works well.

[WeiqunZhang]

I am curious and would like to understand how our users are using it. Do you mind show us some code snippets?

[wuxf99]

I used the AMReX to configure the latest FLASH (FLASHX).

[WeiqunZhang]

I see. There is a Fortan wrapper, amrex_mfiter_allow_multiple in amrex_multifab_module.

[kweide]

@wuxf99 I think this can be closed?

[wuxf99]

Yes.

Thanks, Xingfu

On Apr 27, 2021, at 1:37 PM, Klaus @.***> wrote:

 @wuxf99 I think this can be closed?

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[nw236]

Hi, I had the same error message and wanted to know what caused it as I could not find obvious programming errors.

It turned out that I've used phi.setVal(0.0) and MultiFab::Copy(...) inside the mfiter loop. Moving these out of the loop solved the issue.

Hope this helps others. Nils