[Swig-user] Threading and C++ to Java callbacks

[Sam H. <she...@gr...>]

We have been using SWIG with great success to wrap a c++ library and use the
directors to directly subclass the callback classes in java. This works but
we recently turned on "thread id" in our logger output and we noticed that
every callback appears to have a new thread (as far as java is concerned
anyways). We are using ASIO in the c++ library so I know as a fact that
there is only one thread running in the c++ library so all calls out of the
c++ code should be on the same thread. I saw the preprocessor
settings SWIG_JAVA_ATTACH_CURRENT_THREAD_AS_DAEMON
and SWIG_JAVA_NO_DETACH_CURRENT_THREAD but they don't
seem immediately useful. It may be that this is just an artifact of the way
java handles native threads but I am beginning to think a new java thread
wrapper is generated for every call which may be churning alot of memory. I
am using SWIG 1.3.40.  Has anyone else seen this issue and if so
have recommendations for how to fix it?

Thanks

Sam Hendley