I'm pretty sure you're only meant to run one gtk-main (at any one time).  It'd be nice if guile or guile-gtk could protect against any ill effects of running two, but I'm not sure where the actual problem lies.

hello,

I am using multiple threads within a guile-gtk application.

a call to (gtk-threads-ensure-handler) ensures that a first thread gets started, and
allows the rest of my program to execute. At the end of that program, I call (gtk-main), to
wait in the Gtk event thread.

If I run my program without starting a second thread, it is ok, but as soon as I invoke
(gtk-threads-ensure-handler), my CPU is used at 100%

NOTES:

1: I configured guile-1.6.1 using the "--with-threads" flag.
2: if I strace my process, I see this:

ioctl(7, FIONREAD, [0])                 = 0
select(32, [6 7], [], [], {0, 0})       = 1 (in [6], left {0, 0})
gettimeofday({1041338430, 454970}, NULL) = 0
gettimeofday({1041338430, 455055}, NULL) = 0
ioctl(7, FIONREAD, [0])                 = 0
select(32, [6 7], [], [], {0, 0})       = 1 (in [6], left {0, 0})
gettimeofday({1041338430, 455767}, NULL) = 0
gettimeofday({1041338430, 455852}, NULL) = 0
ioctl(7, FIONREAD, [0])                 = 0
select(32, [6 7], [], [], {0, 0})       = 1 (in [6], left {0, 0})
gettimeofday({1041338430, 456429}, NULL) = 0
gettimeofday({1041338430, 456511}, NULL) = 0
ioctl(7, FIONREAD, [0])                 = 0
select(32, [6 7], [], [], {0, 0})       = 1 (in [6], left {0, 0})
gettimeofday({1041338430, 457084}, NULL) = 0
gettimeofday({1041338430, 457166}, NULL) = 0
ioctl(7, FIONREAD, [0])                 = 0
select(32, [6 7], [], [], {0, 0})       = 1 (in [6], left {0, 0})
gettimeofday({1041338430, 459008}, NULL) = 0
gettimeofday({1041338430, 459097}, NULL) = 0
ioctl(7, FIONREAD, [0])                 = 0
select(32, [6 7], [], [], {0, 0})       = 1 (in [6], left {0, 0})
gettimeofday({1041338430, 459688}, NULL) = 0
gettimeofday({1041338430, 459771}, NULL) = 0
ioctl(7, FIONREAD, [0])                 = 0
select(32, [6 7], [], [], {0, 0})       = 1 (in [6], left {0, 0})

and so on....

--> I suspect a bug in the implementation of

coop_wait_for_runnable_thread () in libguile/isselect.c

if (QFIRST (coop_global_sleepq)->timeoutp)
    gettimeofday (&now, NULL);
 
  return coop_wait_for_runnable_thread_now (&now);

...

thanks a lot,

Stan