Bug in nexusSrc (or NDFileNexus in ADCore)

[MarkRivers]

When saving files in Stream mode with NDFileNexus we now get these errors from the HDF5 library:

auto_settings.sav: 2654 of 2685 PV's connected
HDF5-DIAG: Error detected in HDF5 (1.10.1-pre1) thread 140652121667328:
  #000: ../H5A.c line 512 in H5Aopen_by_name(): can't open attribute
    major: Attribute
    minor: Can't open object
  #001: ../H5Aint.c line 453 in H5A_open_by_name(): unable to load attribute info from object header
    major: Attribute
    minor: Unable to initialize object
  #002: ../H5Oattribute.c line 530 in H5O_attr_open_by_name(): can't locate attribute: 'napimount'
    major: Attribute
    minor: Object not found
HDF5-DIAG: Error detected in HDF5 (1.10.1-pre1) thread 140652121667328:
  #000: ../H5A.c line 512 in H5Aopen_by_name(): can't open attribute
    major: Attribute
    minor: Can't open object
  #001: ../H5Aint.c line 453 in H5A_open_by_name(): unable to load attribute info from object header
    major: Attribute
    minor: Unable to initialize object
  #002: ../H5Oattribute.c line 530 in H5O_attr_open_by_name(): can't locate attribute: 'napimount'
    major: Attribute
    minor: Object not found
HDF5-DIAG: Error detected in HDF5 (1.10.1-pre1) thread 140652121667328:
  #000: ../H5A.c line 512 in H5Aopen_by_name(): can't open attribute
    major: Attribute
    minor: Can't open object
  #001: ../H5Aint.c line 453 in H5A_open_by_name(): unable to load attribute info from object header
    major: Attribute
    minor: Unable to initialize object
  #002: ../H5Oattribute.c line 530 in H5O_attr_open_by_name(): can't locate attribute: 'napimount'
    major: Attribute
    minor: Object not found

This needs to be tracked down and fixed.

[MarkRivers]

I think this may be a problem with disabling error reporting.

napi.c contains the following:

NXMDisableErrorReporting();
attStatus = NXgetattr(fid, "napimount", nxurl, &length, &type);
NXMEnableErrorReporting();

So it looks like it tries to turn off error messages before it calls NXgetattr. So perhaps this is just not working.

[MarkRivers]

It appears that NXMDisableErrorReporting() only disables error messages from the Nexus code, not from the underlying HDF5 library. The messages above are from the HDF5 library. It is possible they are happening because I am building a Debug release of HDF, rather than a Production release, but I don't think so.

Has anyone seen these errors before, or have any idea how to suppress them. It looks to me like the Nexus library is trying to see if an attribute called "napimount" is present, but it does that in a way that if it is not present we get errors from the HDF5 library.

[MarkRivers]

Some more information:

• The above error does not happen on Windows in either Single or Stream mode.
• The above error does not happen on Linux in Single mode
• The above error happen on Linux in Stream mode.

I can get the error to go away on Linux by doing the following:

• Set LazyOpen=Yes and save images in Stream mode. No errors.
• When changing back to LazyOpen=No then the errors still do not occur. So saving images with LazyOpen=Yes at least once fixes the problem.

[ulrikpedersen]

I haven't really used the NeXus library and this doesn't ring any bells... @PeterC-DLS - do you understand why the NeXus library may be trying to look for the "napimount" attribute in such a brutal manner?

[PeterC-DLS]

Hi Ulrik, I’m not sure what the context of this is (I’m not on this repo). However, my knowledge is that NeXus had their own standard for referring to external datasets by having a (empty) placeholder dataset with an attribute named “napimount”. The content of this attribute conforms to a URI scheme called “nxfile” and this references a file path and target within that file in a similar manner to external links in HDF5. Regards, Peter From: Ulrik Kofoed Pedersen [mailto:notifications@github.com] Sent: 16 May 2017 09:35 To: areaDetector/ADSupport <ADSupport@noreply.github.com> Cc: Chang, Peter (DLSLtd,RAL,LSCI) <Peter.Chang@Diamond.ac.uk>; Mention <mention@noreply.github.com> Subject: Re: [areaDetector/ADSupport] Bug in nexusSrc (or NDFileNexus in ADCore) (#9) I haven't really used the NeXus library and this doesn't ring any bells... @PeterC-DLS<https://github.com/peterc-dls> - do you understand why the NeXus library may be trying to look for the "napimount" attribute in such a brutal manner? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub<#9 (comment)>, or mute the thread<https://github.com/notifications/unsubscribe-auth/ABUVVx62FPl3gV6t65HBS8J-8WLVkjnbks5r6V-cgaJpZM4M8EdB>.

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