Inexplicable blocking when Xerces is called from Perl5

[RHS Linux User]

        I am actively integrating XERCES into Perl5 on UNIX, using SWIG.
In order to get needed functionality (and experiment with the code), I
have created some InputSources based on the standard C++ stream classes,
specifically fstream and strstream.  The resulting classes are called
"StrStreamInputSource" and "FStreamInputSource".

        -- These classes work quite well from C++. --  However, when I
SWIG them into Perl5, they start acting up.  Specifically, the InputSource
based on the istrstream class, "StrStreamInputSource".  I can create an
StrStreamInputSource object just fine in Perl.  However when I attempt to
pass it to a DOMParser object, the script goes into an everlasting sleep.
Specifically, it is blocking on a "read" operation call for an istrstream
object.  This call occurs in the BinStreamInputStream class -- an
object of this class is returned by a call to "makeStream" on a
StrStreamInputSource object.

        Here's the output from the "ps -aefl" command:

  F S UID        PID  C PRI  NI ADDR  WCHAN         CMD
000 S root     29698  7 78    0 -     rt_sigsuspend perl ./DOMPrint3.pl