g++ 3.0.2 bug: unable to catch exceptions thrown from subthreads during destruction of global objects in shared libraries

[Carolyn Wasikowski]

[Note:  I attempted to submit this bug to
http://gcc.gnu.org/cgi-bin/gnatsweb.pl, but was unable to attach more than
one file to the bug report.  Since the bug involves two source files--one
for main() and the other for a shared library--you're getting email with
MIME attachments instead.  Hope this isn't too inconvenient.]

Reporter's email:  jc@roguewave.com

Category:  c++ - C++ front end

Synopsis:  unable to catch exceptions thrown from subthreads during
destruction of global objects in shared libraries

Confidential:  no

Severity:  critical

Priority:  high

Class:  sw-bug

Release:  The complete output of g++ -v is:
	Reading specs from
/package/1/compilers/g++/3.0.2/bin/../lib/gcc-lib/sparc-sun-solaris2.8/3.0.2
/specs
	Configured with: ../gcc-3.0.2/configure
--prefix=/nfs/packages/mdx/Solaris/compilers/g++/3.0.2
	Thread model: posix
	gcc version 3.0.2

Environment:  Solaris 8 (SunOS 5.8)

Description:
	With gcc 3.0.2 or 3.0.1 (but not 2.96 or 2.95), under very
particular circumstances, some exceptions will not be caught.

	Specifically, if an exception is thrown from a subthread after
main() has returned but before the main thread has terminated (that is,
during the destruction of a global object), then the exception cannot be
caught if the global object resides within a shared library.

	Instead, abort() is called and the program terminates on SIGKILL.
The stack trace is as follows:

		#0  0xff059bf0 in __sigprocmask () from
/usr/lib/libthread.so.1
		#1  0xff04e628 in _resetsig () from /usr/lib/libthread.so.1
		#2  0xff04dd18 in _sigon () from /usr/lib/libthread.so.1
		#3  0xff050e8c in _thrp_kill () from /usr/lib/libthread.so.1
		#4  0xff0c9b10 in raise () from /usr/lib/libc.so.1
		#5  0xff0b512c in abort () from /usr/lib/libc.so.1
		#6  0xff251528 in ?? ()
		    at
../../../../gcc-3.0.2/libstdc++-v3/libsupc++/vec.cc:52
		   from /package/1/compilers/g++/3.0.2/lib/libstdc++.so.3
		#7  0xff251574 in ?? ()
		    at
../../../../gcc-3.0.2/libstdc++-v3/libsupc++/vec.cc:52
		   from /package/1/compilers/g++/3.0.2/lib/libstdc++.so.3
		#8  0xff2516e0 in ?? ()
		    at
../../../../gcc-3.0.2/libstdc++-v3/libsupc++/vec.cc:52
		   from /package/1/compilers/g++/3.0.2/lib/libstdc++.so.3
		#9  0x13e5c in spew (arg=0x0) at thr.cpp:18

	If any of the conditions are not met--if the exception is thrown
before main() returns, if the exception is thrown from the main thread
rather than a subthread, or if the global object resides in a static
library--then the exception can be caught, and the program can terminate
normally.

File attachments:
	global.ii.gz is a gzipped, preprocessed source file.  global.output
is the output produced when creating global.ii via:

		g++ -v -save-temps -Wall -pthreads -g -c global.cpp -fPIC
-mimpure-text -shared 

 <<global.ii.gz>>  <<global.output>> 
	Likewise, thr.ii.gz is a gzipped, preprocessed source file, and
thr.output is the output produced when creating thr.ii via:

		g++ -v -save-temps -Wall -pthreads -g -c thr.cpp

 <<thr.ii.gz>>  <<thr.output>> 
How to repeat:
	Compile global.ii into a shared library with:

		gunzip global.ii.gz
		g++ -pthreads global.ii -fPIC -mimpure-text -shared -o
libglobal.so

	Compile thr.ii into a test case with:

		gunzip thr.ii.gz
		g++ -pthreads thr.ii -L. -o thr -lglobal -lposix4 -lpthread
-lnsl

	Run the test case with:

		export LD_LIBRARY_PATH=`pwd`:$LD_LIBRARY_PATH
		./thr

	The test case begins by creating a subthread.  The main thread and
the subthread then begin to periodically print diagnostics to cout.  After
main() finishes with these diagnostics, it sets a flag to indicate that the
shutdown process has begun.  After main() returns, the destructor for a
Global object in libglobal.so begins to print statements to cout; this
prevents the main thread from terminating, and allows the subthread to
continue running.  Before printing its next diagnostic statement, the
subthread notices the shutdown flag and throws an exception.  Its attempt to
catch this exception fails with gcc 3.0.1 and 3.0.2, but succeeds with other
compilers and earlier versions of gcc.

-JC

jc@roguewave.com
http://www.roguewave.com
(541)754-4094

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