[Difx-users] Multi-thread 4-bit VDIF fails with 'vdifmux() failed with return code -2014' {External} {External} {External} {External}

[Jacob Brooks]

Thanks to both of you for the response. I have made the requested files available on a public server which you should be able to access. I'll send the details in a separate email...

As I was checking everything I tried running DiFX on the recorded files rather than the network streams and it didn't throw an error, so whatever the problem is it only seems to occur when reading from a network
________________________________
From: Difx-users <difx-users-bounces at listmgr.nrao.edu> on behalf of Adam Deller via Difx-users <difx-users at listmgr.nrao.edu>
Sent: 20 February 2025 22:26
To: Walter Brisken <wbrisken at nrao.edu>
Cc: difx-users at listmgr.nrao.edu <difx-users at listmgr.nrao.edu>
Subject: Re: [Difx-users] Multi-thread 4-bit VDIF fails with 'vdifmux() failed with return code -2014' {External} {External} {External}

I agree that a data sample is needed to properly assist (or the output of printVDIF or similar might already help too - basically a summary of what is in the headers). My initial guess is an issue with either the threadIDs or the number of channels per thread that is being placed in the VDIF header.

Cheers,
Adam

On Fri, 21 Feb 2025 at 03:03, Walter Brisken via Difx-users <difx-users at listmgr.nrao.edu<mailto:difx-users at listmgr.nrao.edu>> wrote:

Hi Jake,


It would be most useful if you could make available the .input file and a sample of the VDIF stream (perhaps a couple to a couple hundred MB made available through http) that you are dealing with.  The .vex file is also a useful source of info if that can be shared.


Cheers,


Walter


On 2/20/25 05:12, Jacob Brooks via Difx-users wrote:
Hi all,

We're currently trying to get DiFX working with the following setup: 4-bit, 2 channel (L + R pols), 2 threads (2 subbands), delivered in real time via UDP. It has been working fine up until the point where we tried adding a second thread - single-thread VDIF has been working for us.

When running in multi-threaded mode, the datastream processes crash with the following message:

'vdifmux() failed with return code -2014, likely input buffer is too small!'

I have managed to trace the problem to a check in 'getLowestFrameNumber' in vdifio/src/vdifmux.c. The inequality check in that function:

'getVDIFNumChannels(vh) != vm->inputChannelsPerThread'

succeeds as the function returns a value of 2 while 'inputChannelsPerThread' has a value of 1. This happens for every iteration so vdifmux() fails and returns a -2014 error code.

I'm not sure where to go from here and was hoping someone more familiar with DiFX could help out. Hopefully I'm not missing something obvious! If you need any more information I haven't provided please do ask.

Cheers,
Jake



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Prof. Adam Deller
Centre for Astrophysics & Supercomputing
Swinburne University of Technology
John St, Hawthorn VIC 3122 Australia
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