Re: [Boost-users] [Serialization] Sometimes Fails Reading BinaryFile

Subject: Re: [Boost-users] [Serialization] Sometimes Fails Reading BinaryFile
From: Robert McCullough (rob_at_[hidden])
Date: 2010-06-17 12:23:43

> -----Original Message-----
> From: boost-users-bounces_at_[hidden] [mailto:boost-users-
> bounces_at_[hidden]] On Behalf Of Robert Ramey
> Sent: Thursday, June 17, 2010 12:20 PM
> To: boost-users_at_[hidden]
> Subject: Re: [Boost-users] [Serialization] Sometimes Fails Reading
BinaryFile
> 
> Robert McCullough wrote:
> > Steven,
> >
> > Does the Serialization library support multi-thread application.
> > My application uses boost::archive::binary_iarchive and
> > boost::archive::binary_oarchive to serialize data to/from files in
> > several different threads.
> 
> What could this mean?
> 
> That multiple threads read/write to the same open archive? Of course this
> could never make sense.
> 
> That multiple archives are being used simultaneously by different threads?
> As far as I know, subject to the following, there should be no problem.
> 

[Robert McCullough] 
It means that multiple archives are being used simultaneously by different
threads.
Ok, this seems to work.  I removed all the other archives from the threads
so that there is only one archive.
I still have my problem, so I don't think this is my issue. 

> a) If serialization code for some class is in a DLL and this DLL is
dynamically
> loaded/unloaded while some other archive is open and being used by a
> separate thread, there could be a problem.  This would be due to the fact
> that there is global list of types which is updated when a DLL is loaded
and/or
> unloaded.
> 
[Robert McCullough] 
Ok, I am not using DLL's.

> b) xml_iarchives depend upon spirit which is not guarenteed thread-safe.
I
> looked at the spirit code and believe that I selected that part which was
> thread-safe.  But at least one user noted an issue with loading multiple
> xml_iarchives from separate threads.
> 
[Robert McCullough] 
Ok.  I will keep that in mind if I use xml_iarchives.

> > I believe this might be happing at the same time.
> > Could this be causing my problem?
> 
> This question suggests to me that you're going about addressing your
> problem in totally the wrong way.  I would suggest you make a unit test
for
> your serialization code.  Look at the tests in the serialization library
for
> inspiration.  This might seem like extra work - but it's not.  It saves
time.  Do
> the following.
> 
> a) Make a one or more small test programs which test JUST the
serialization
> of your classes.
> b) Run these test programs on ALL the archive classes in the the library
> including text and xml.  If your serialization functions are correctly
written,
> the ALL archive classes should work.
> c) Consider making a separate test program for each class.
> On my system, anytime I make a change in one class, all tests using that
class
> are automatically recompiled and re-run.  This saves huge amounts of
wasted
> time in the future.
> 
[Robert McCullough] 
Ok, thanks for the advice.

> I seem to recall that one problem is that you were using binary_archive to
try
> to read archives created on a different platform.  This is not supported
by the
> binary_archive - and this is clearly stated in the documentation.  If
you're
> doing this, this can never work.
>
[Robert McCullough] 
 Yes, I realized that this would not work on different platforms.
I was just testing my code on different platforms to see if the bug happened
on both.
Then I realized I could not read the same archive file on both platforms.

> Robert Ramey
> 
> 
> >
> > Thanks,
> > Robert
> >
> 
> 
> 
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