Pthreads and GDB?

Tue Jul 12 17:17:00 GMT 2011

The 2 threads finish executing before I can set a break. Why? ---Jan
On Tue, Jul 12, 2011 at 1:15 PM, Jan Chludzinski
<jan.chludzinski@gmail.com> wrote:
> Sorry, I forgot to build with the -g option.
>> But still as I'm stepping passed the 2 pthread_create() routines they
> finish executing before I can set a break.  Why?
>> ---Jan
>>> On Tue, Jul 12, 2011 at 1:02 PM, Jan Chludzinski
> <jan.chludzinski@gmail.com> wrote:
>>> Since cygwin1.dll is multithreaded, I routinely set breakpoints which
>>> are only hit in a thread.  So, yes, gdb is supposed to be multi-thread
>>> aware.
>>>> I have a 2 thread program.  I set the break for main() and run (to main):
>>>>      (gdb) b main
>>      Breakpoint 1 at 0x401191
>>      (gdb) r
>>      Starting program: /home/John/projects/pthreads/test1/a.exe
>>      [New thread 3680.0x13e8]
>>      Error: dll starting at 0x76ff0000 not found.
>>      Error: dll starting at 0x76590000 not found.
>>      Error: dll starting at 0x76ff0000 not found.
>>      Error: dll starting at 0x76c40000 not found.
>>      [New thread 3680.0xc7c]
>>      Breakpoint 1, 0x00401191 in main ()
>>>> Wait a few seconds and start to step:
>>>>      (gdb) n
>>      Single stepping until exit from function main,
>>      which has no line number information.
>>      [New thread 3680.0x1410]
>>      [New thread 3680.0x1540]
>>      Counter value functionCount1: 1
>>      Counter value functionCount2: 2
>>      ...
>>      Final count: 10
>>      Program exited normally.
>>>> As you can see the threads have finished executing, along with the
>> main thread, *before * I ever get a chance to step to the first
>> pthread_create().  Let alone set a break in a thread.
>>>> Why?
>>>> Thanks, Jan
>>>> On Tue, Jul 12, 2011 at 6:16 AM, Jan Chludzinski
>> <jan.chludzinski@gmail.com> wrote:
>>> I went to GNU.org to read about GDB and threads since I'm having
>>> trouble working with ptheads under GDB on Cygwin.  I notice this on
>>> the GNU.org web site:
>>>>>> "Warning: These facilities are not yet available on every GDB
>>> configuration where the operating system supports threads. If your GDB
>>> does not support threads, these commands have no effect. For example,
>>> a system without thread support shows no output from `info threads',
>>> and always rejects the thread command, like this:"
>>>>>> What the level of support for threads with GDB under Cygwin?
>>>>>> Switching between threads causes seg-faults.  Also, I thought that
>>> while you're stepping through one thread, the other threads weren't
>>> running? Shouldn't I be able to set a breakpoint in a thread before
>>> pthread_create() is invoked?  Doesn't appear to be the case?
>>>>>> ---Jan
>>>>>>
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