Re: threading woes

[Nick Glencross <nickg glencros demon co uk>]

Great work Bowie. I shall give it a go later this (UK) afternoon.

Nick


Bowie Owens wrote:

> Bowie Owens wrote:
>
> > Hi,
> >
> > I received a request for some help on the orbitcpp-list. It relates 
> > to using threading as part of the implementation of a servant (but 
> > not using POA threading policies). The IDL looks kind of like this:
> >
> > module test {
> >        interface Worker {
> >                void ping ();
> >        };
> >
> >        interface Master {
> >                void create_thread ();
> >                void submit_work (in Worker server);
> >        };
> > };
> >
> > The Master servant in creates a new thread using glib in the 
> > create_thread() method. It the receives a reference to a Worker 
> > servant (in a different process) from the submit_work() method. The 
> > master then calls the ping() method on the Worker object. If the 
> > ping() is called in the same thread as the main loop, everythings 
> > works fine. However, if the ping() is called from the thread created 
> > in create_thread() the ORB drops out of its main loop and things fall 
> > apart. I've attached a log of ORBIT2_DEBUG=all. For the adventurous 
> > this is checked in to CVS under orbitcpp/test/cpp/threading. I was 
> > wondering if anyone had any insight into why the ORB is dropping out 
> > of its run loop or how I can find out why.
>
>
> I've just worked it out myself. The program is using the linc_loop and 
> the g_main_loop_quit (link_loop) is happening within 
> link_exec_set_io_thread() which is getting called indirectly from 
> giop_thread_new_check() (see backtrace below). I needed to ensure that 
> link_set_io_thread(TRUE) is called before the run loop is entered. 
> Nick, this can be achieved by using the passing orb identifier 
> "orbit-io-thread" to CORBA::ORB_init(). However, I think this is bug 
> since it seems like the intention is that we can switch transparently 
> from non-threaded io to threaded io. I've attached a patch which 
> causes giop_main_run() to enter the giop_main_loop after we quit the 
> link_loop if giop_thread_io() has become true.
>
> #0  link_exec_set_io_thread (data=0xbf7ff8c4, immediate=1) at linc.c:379
> #1  0x4007b2a7 in link_dispatch_command (data=0xbf7ff8c4, immediate=1)
>    at linc.c:447
> #2  0x4007aac6 in link_exec_command (cmd=0xbf7ff8c4) at linc.c:115
> #3  0x4007b22f in link_set_io_thread (io_in_thread=1) at linc.c:432
> #4  0x4005493f in giop_thread_new_check (opt_self=0x80646c8) at 
> giop.c:826
> #5  0x4005c018 in ORBit_small_invoke_stub (obj=0x80671c0, 
> m_data=0x8056800,
>    ret=0x0, args=0x0, ctx=0x0, ev=0xbf7ffa3c) at orbit-small.c:629
> #6  0x4005be7c in ORBit_small_invoke_stub_n (object=0x80671c0,
>    methods=0x8056864, index=0, ret=0x0, args=0x0, ctx=0x0, ev=0xbf7ffa3c)
>    at orbit-small.c:575
> #7  0x400745e9 in ORBit_c_stub_invoke (obj=0x80671c0, methods=0x8056864,
>    method_index=0, ret=0x0, args=0x0, ctx=0x0, ev=0xbf7ffa3c, class_id=1,
>    method_offset=4, skel_impl=0x80531a4 
> <_ORBIT_skel_small_test_Worker_ping>)
>    at poa.c:2640
> #8  0x08054642 in test_Worker_ping ()
> #9  0x080532f6 in test::Worker::ping() ()
> #10 0x08050c7f in server_thread::consumer() ()
> #11 0x08050afd in server_thread::thread_consumer(void*) ()
> #12 0x401931f4 in g_thread_create_proxy ()
>   from /local_scratch/owe043/opt/gnome2/lib/libglib-2.0.so.0
> #13 0x400ffc0e in pthread_start_thread_event () from /lib/libpthread.so.0
>
> ------------------------------------------------------------------------
>
> Index: ./src/orb/GIOP/giop.c
> ===================================================================
> RCS file: /cvs/gnome/ORBit2/src/orb/GIOP/giop.c,v
> retrieving revision 1.50
> diff -u -p -r1.50 giop.c
> --- ./src/orb/GIOP/giop.c	4 Mar 2004 17:49:37 -0000	1.50
> +++ ./src/orb/GIOP/giop.c	21 Dec 2004 01:06:54 -0000
> @@ -597,6 +597,9 @@ static GMainLoop *giop_main_loop = NULL;
> void
> giop_main_run (void)
> {
> +	if (!giop_thread_io ())
> +		link_main_loop_run ();
> +
> 	if (giop_thread_io ()) {
> 		g_assert (giop_thread_self () == giop_main_thread);
> 		g_assert (giop_main_loop == NULL);
> @@ -604,8 +607,7 @@ giop_main_run (void)
> 		g_main_loop_run (giop_main_loop);
> 		g_main_loop_unref (giop_main_loop);
> 		giop_main_loop = NULL;
> -	} else
> -		link_main_loop_run ();
> +	} 
> }
>
> void
>