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[netCDF #UPO-861727]: getVar crashed with compressed file

Ok, it sounds like the netcdf-c library per-se is ok (else nccopy
would fail). So, the problem would seem to be in either your program
or in getVar().

What I would like to see is the arguments to getVar that are failing
plus the ncdump output of that specific variable. I would be looking
to make sure that the arguments are consistent with the actual
variable definition. You could try doing some print statements
before the getVar, or if you are on Linux, you could use gdb
to put a breakpoint inside getVar.

> Correct. I can read step (3), but not step (2).
> 
> The program is proprietary. Is there something you can suggest me to try ?
> 
> Thanks,
> 
> Norman
> 
> -----Original Message-----
> From: Unidata netCDF Support <address@hidden>
> Sent: Sunday, July 29, 2018 5:48 PM
> To: Lo, Norman <address@hidden>
> Cc: address@hidden; Lo, Norman <address@hidden>
> Subject: [netCDF #UPO-861727]: getVar crashed with compressed file
> 
> So I read your response to mean that nccopy can read b.nc (step 3) but your 
> program cannot read b.nc using getVar().
> Is the program small enough (and non-proprietary) so that you can send it to 
> me to try out?
> 
> > The steps are correct. When I try to read the c.nc file again, the program 
> > does not actually crash (Sorry I described the situation incorrectly), 
> > instead, it's just freeze at the call for a long time (CPU is running 
> > 100%). So I have to break it eventually.
> >
> > I tried to do the following:
> >
> > (1) original file: a.nc
> > (2) compress a.nc to become b.nc  (using nccopy -d 1)
> > (3) decompress b.nc to become c.nc. (using nccopy -d 0)
> >
> > I can read the c.nc file fine.
> >
> >
> > Thank you very much for your time,
> >
> > Norman
> >
> >
> > -----Original Message-----
> > From: Unidata netCDF Support <address@hidden>
> > Sent: Thursday, July 26, 2018 10:30 PM
> > To: Lo, Norman <address@hidden>
> > Cc: address@hidden
> > Subject: [netCDF #UPO-861727]: getVar crashed with compressed file
> >
> > Let me make sure I understand.
> > 1. You have some uncompressed file, call it u.nc.
> > 2. You compress it using nccopy -d 1 u.nc c.nc to produce the file
> > c.nc 3. You then try to read the c.nc file using a program that calls
> > getVar and when you do so, your program crashes.
> > Do I have that right?
> >
> > >
> > > We have  program that uses the netcdf-cxx-4.2 interface to manipulate 
> > > data stored in netcdf files. As far as I can tell, everything works fine 
> > > if the netcdf files are not compressed.
> > >
> > > However, if I use "nccopy -d 1" to compress the files. The function 
> > > getVar crashed.
> > >
> > >
> > > The function we are using is:
> > >
> > >
> > > void netCDF::NcVar::getVar        (              const std::vector< 
> > > size_t > &        start,
> > > const std::vector< size_t > &        count,
> > > const std::vector< ptrdiff_t > & stride, const std::vector<
> > > ptrdiff_t
> > > > & imap, short * dataValues
> > > )                              const
> > >
> > >
> > >
> > >
> > > Could you let me know if I did something wrong? Thank you very much,
> > >
> > > Norman
> > >
> > >
> >
> > =Dennis Heimbigner
> > Unidata
> >
> >
> > Ticket Details
> > ===================
> > Ticket ID: UPO-861727
> > Department: Support netCDF
> > Priority: High
> > Status: Open
> > ===================
> > NOTE: All email exchanges with Unidata User Support are recorded in the 
> > Unidata inquiry tracking system and then made publicly available through 
> > the web.  If you do not want to have your interactions made available in 
> > this way, you must let us know in each email you send to us.
> >
> >
> >
> 
> =Dennis Heimbigner
> Unidata
> 
> 
> Ticket Details
> ===================
> Ticket ID: UPO-861727
> Department: Support netCDF
> Priority: High
> Status: Open
> ===================
> NOTE: All email exchanges with Unidata User Support are recorded in the 
> Unidata inquiry tracking system and then made publicly available through the 
> web.  If you do not want to have your interactions made available in this 
> way, you must let us know in each email you send to us.
> 
> 
> 

=Dennis Heimbigner
  Unidata


Ticket Details
===================
Ticket ID: UPO-861727
Department: Support netCDF
Priority: High
Status: Open
===================
NOTE: All email exchanges with Unidata User Support are recorded in the Unidata 
inquiry tracking system and then made publicly available through the web.  If 
you do not want to have your interactions made available in this way, you must 
let us know in each email you send to us.