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

Subject: Re: [Boost-users] [Serialization] Sometimes Fails Reading BinaryFile
From: Robert Ramey (ramey_at_[hidden])
Date: 2010-06-17 12:20:26

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.

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.

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.

> 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.

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 Ramey

>
> Thanks,
> Robert
>