Re: stack trace of the right thread on error

Hm.

I think the current behavior is straightforward implementation of SRFI-18,
although SRFI-18 isn't very specific about the situation.

When a thread throws an exception and where no user-defined exception
handler is installed, it should call thread's "initial exception handler",
which should terminate the thread.  When you call thread-join! on the
thread terminated by such a way, the calling thread gets uncaught-exception.

So, the proper way is to handle the exception in each thread,
probably using with-error-handler.  (SRFI-18's with-exception-handler
is very low level in terms of continuation handling; specifically,
you need to use call/cc explicitly if you want to abort the operation
when an exception is raised).

However, it is possible to let the initial exception handler call
report-error before terminating the thread, so that you can see the
stack trace of the thread that raised the error.   In such a case,
you'll see two error strack traces (one from the error-causing thread,
another from the thread that calls thread-join!) unless you handles
thread's error by yourself.
Try the following patch and let me know how you like.

--shiro

===================================================================
RCS file: /cvsroot/gauche/Gauche/ext/threads/threads.c,v
retrieving revision 1.5
diff -c -r1.5 threads.c
*** threads.c	5 Jul 2003 03:29:11 -0000	1.5
--- threads.c	9 Feb 2004 11:50:30 -0000
***************
*** 135,140 ****
--- 135,141 ----
                  exc = Scm_MakeThreadException(SCM_CLASS_UNCAUGHT_EXCEPTION, vm);
                  SCM_THREAD_EXCEPTION(exc)->data = SCM_OBJ(vm->escapeData[1]);
                  vm->resultException = exc;
+                 Scm_ReportError(SCM_OBJ(vm->escapeData[1]));
                  break;
              }
          } SCM_END_PROTECT;

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