http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55917
Bug #: 55917
Summary: Impossible to find/debug unhandled exceptions in an
std::thread
Classification: Unclassified
Product: gcc
Version: 4.7.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: tob...@ringis.se
If an unhandled exception occurs in an std::thread, the stack is unwound before
std::terminate is called, which makes it impossible to find the location of the
exception.
I emailed gcc-help about this about a year ago, and learned that a fix was
supposed to be applied for 4.7, but that fix didn't work out. Here's my post:
http://gcc.gnu.org/ml/gcc-help/2011-11/msg00140.html
The reason for the unwound stack is that libstdc++'s function that calls the
user's thread function contains a try/catch all statement. The supposed fix
was to use noexcept on the internal thread main function, and the reason why it
did not work out is described here:
http://gcc.gnu.org/ml/gcc-help/2013-01/msg00068.html
I've tested 4.6, 4.7 and a 4.8 snapshot with identical results. See the
attached test program tmp4.cpp. Compile with:
g++ -std=c++0x -g tmp4.cpp -lpthread
Run in gdb:
~> gdb a.out
[...]
(gdb) r
Starting program: /home/tobias/a.out
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
[New Thread 0x7ffff7fd0700 (LWP 10278)]
terminate called after throwing an instance of 'std::runtime_error'
what(): foo
Program received signal SIGABRT, Aborted.
[Switching to Thread 0x7ffff7fd0700 (LWP 10278)]
0x000000318f036285 in raise () from /lib64/libc.so.6
Missing separate debuginfos, use: debuginfo-install
glibc-2.14.90-24.fc16.9.x86_64 libgcc-4.6.3-2.fc16.x86_64
libstdc++-4.6.3-2.fc16.x86_64
(gdb) bt
#0 0x000000318f036285 in raise () from /lib64/libc.so.6
#1 0x000000318f037b9b in abort () from /lib64/libc.so.6
#2 0x00000031964bbc5d in __gnu_cxx::__verbose_terminate_handler() ()
from /usr/lib64/libstdc++.so.6
#3 0x00000031964b9e16 in ?? () from /usr/lib64/libstdc++.so.6
#4 0x00000031964b9e43 in std::terminate() () from /usr/lib64/libstdc++.so.6
#5 0x0000003196470b0b in ?? () from /usr/lib64/libstdc++.so.6
#6 0x000000318fc07d90 in start_thread () from /lib64/libpthread.so.0
#7 0x000000318f0f119d in clone () from /lib64/libc.so.6
(gdb)
As you can see, neither the thread's main function, nor foo() is in the
backtrace.
