debugging threads

debugging threads

[Tim Michals]

Hello,

I'm trying to debug simple multithreaded app and get the following error:
[Thread debugging using libthread_db enabled]
Cannot find new threads: generic error

Can set break points and trace as shown below.
(gdb) 
Here is the info..

GNU gdb Red Hat Linux (6.6-15.fc7rh)
Copyright (C) 2006 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain
conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i386-redhat-linux-gnu"...
Using host libthread_db library "/lib/libthread_db.so.1".
(gdb) list
9       #include <iostream>
10
11      void helloworld(const char* who)
12      {
13          std::cout << who << "says, \"Hello World.\"" << std::endl;
14      }
15
16      int main()
17      {
18          boost::thread thrd(boost::bind(&helloworld, "Bob"));
(gdb) list
19          thrd.join();
20      }
21
(gdb) b main
Breakpoint 1 at 0x8048320: file ../helloworld.cpp, line 18.
(gdb) run
Starting program: /home/tcmichals/workspace/example/Debug/example
[Thread debugging using libthread_db enabled]
Cannot find new threads: generic error
(gdb) n
Single stepping until exit from function _start,
which has no line number information.
Cannot find user-level thread for LWP 3719: generic error
(gdb) n
Single stepping until exit from function _start,
which has no line number information.
Cannot find user-level thread for LWP 3719: generic error

The kernel version is:
Linux version 2.6.22.4-65.fc7 (kojibuilder@xenbuilder2.fedora.redhat.com)
(gcc v
ersion 4.1.2 20070502 (Red Hat 4.1.2-12)) #1 SMP Tue Aug 21 22:36:56 EDT
2007

Several posting on this issue i.e.
http://sourceware.org/ml/gdb/2007-08/msg00128.html 

Re: debugging threads

[Daniel Jacobowitz]

On Sat, Sep 29, 2007 at 09:59:56PM -0500, Tim Michals wrote:
> GNU gdb Red Hat Linux (6.6-15.fc7rh)

This is a Red Hat version of GDB...

> The kernel version is:
> Linux version 2.6.22.4-65.fc7 (kojibuilder@xenbuilder2.fedora.redhat.com)

... and this is a Red Hat prebuilt kernel.  Normally they work
together fine.  Maybe someon on a Fedora list will know why they don't
in your case.

-- 
Daniel Jacobowitz
CodeSourcery

RE: debugging threads

[Tim Michals]

I've narrowed the issue down it to using -static gcc option version shared
libraries
For example:
Ok, this might be a user error, but... I did exactly what you did and yes it
worked.  I'm using the latest and greatest from boost cvs. So mine is in
/usr/local/lib... So using that library and changing the path ...
[tcmichals@localhost examples]$ g++ -o helloworld helloworld.cpp -Wall
-ggdb2 -
pthread -L/usr/local/lib -lboost_thread-gcc41-mt-d
[tcmichals@localhost examples]$ export LD_LIBRARY_PATH=/usr/local/lib
[tcmichals@localhost examples]$ gdb helloworld
GNU gdb Red Hat Linux (6.6-15.fc7rh)
Copyright (C) 2006 Free Software Foundation, Inc.
Using host libthread_db library "/lib/libthread_db.so.1".
(gdb) b main
Breakpoint 1 at 0x8048a78: file helloworld.cpp, line 17.
(gdb) start
Breakpoint 2 at 0x8048a78: file helloworld.cpp, line 17.
Starting program: /home/tcmichals/examples/helloworld
[Thread debugging using libthread_db enabled]
[New Thread -1209014576 (LWP 2826)]
[Switching to Thread -1209014576 (LWP 2826)]

Breakpoint 1, main () at helloworld.cpp:17
17          boost::thread thrd(&helloworld);
(gdb)
It worked!!!
ok if I do the following:
The program is running.  Exit anyway? (y or n) y
[tcmichals@localhost examples]$ g++ -static -o helloworld helloworld.cpp
-Wall
-ggdb2 -pthread -L/usr/local/lib -lboost_thread-gcc41-mt-d
[tcmichals@localhost examples]$
[tcmichals@localhost examples]$ ls /usr/local/lib/libboost_thread*
/usr/local/lib/libboost_thread-gcc41-mt-1_35.a
/usr/local/lib/libboost_thread-gcc41-mt-1_35.so
/usr/local/lib/libboost_thread-gcc41-mt-1_35.so.1.35.0
/usr/local/lib/libboost_thread-gcc41-mt.a
/usr/local/lib/libboost_thread-gcc41-mt-d-1_35.a
/usr/local/lib/libboost_thread-gcc41-mt-d-1_35.so
/usr/local/lib/libboost_thread-gcc41-mt-d-1_35.so.1.35.0
/usr/local/lib/libboost_thread-gcc41-mt-d.a
/usr/local/lib/libboost_thread-gcc41-mt-d.so
/usr/local/lib/libboost_thread-gcc41-mt.so
[tcmichals@localhost examples]$ gdb helloworld
GNU gdb Red Hat Linux (6.6-15.fc7rh)
Copyright (C) 2006 Free Software Foundation, Inc.
This GDB was configured as "i386-redhat-linux-gnu"...
Using host libthread_db library "/lib/libthread_db.so.1".
(gdb) b main
Breakpoint 1 at 0x80482ac: file helloworld.cpp, line 17.
(gdb) start
Breakpoint 2 at 0x80482ac: file helloworld.cpp, line 17.
Starting program: /home/tcmichals/examples/helloworld
[Thread debugging using libthread_db enabled]
Cannot find new threads: generic error
(gdb)
Then I try to exit gdb and it locks up... But I thought -static links the
static library?  
well, now atleast I know what the difference is and the issue, but don't
know why.

Re: debugging threads

[Daniel Jacobowitz]

On Mon, Oct 01, 2007 at 09:00:11PM -0500, Tim Michals wrote:
> I've narrowed the issue down it to using -static gcc option version shared
> libraries

You need a current CVS snapshot of both gdb and glibc to debug static
applications using NPTL.  It won't be fixed until GDB 6.7 and GLIBC
2.7.

-- 
Daniel Jacobowitz
CodeSourcery