[m-dev.] hang-up in C-code in asm_fast.gc.prof

[Ondrej Bojar]

To make things worse, the hang-up does not occur if a different dataset is used.

Several files opened in the course of computation. The C-code has its own file, 
the Mercury code uses different files to load different things.

- for the C-code I keep exactly the same input file to be loaded (part of which 
is the deletion of the temporary file)
- for Mercury code, I replace the input file with a shorter one.

=> the error does not occur, although the very same system call is performed in 
the C-code.

O.

Ondrej Bojar wrote:
>  > The benchmarking module contains some predicates to turn profiling on
>  > and off.  What happens if you disable profiling before your system 
> call and
>  > enable it afterwards?  (I know that defeats the purpose of profiling,
>  > but ...)
>  >
>  > Julien.
> 
> 
> Hangs right in the call to system(cmd):
> 
> 2-grams: reading 638323 entries
> 
> Breakpoint 1, removefile (filePath=@0x7fffd8a71840) at util.cpp:51
> 51        sprintf(cmd,"rm %s",filePath.c_str());
> Current language:  auto; currently c++
> (gdb) step
> 52        system(cmd);
> (gdb) step
> <hangs forever>
> 
> O.
> 
> 
>> On Thu, 24 May 2007, Ondrej Bojar wrote:
>>
>>> If I understand it correctly, a profiler tick happens at the call to 
>>> system(cmd). After some further steps within the profiler, a 
>>> do_system in libc is called and hangs forever.
>>>
>>> Breakpoint 1, removefile (filePath=@0x7fff43730500) at util.cpp:51
>>> 51        sprintf(cmd,"rm %s",filePath.c_str());
>>> Current language:  auto; currently c++
>>> (gdb) print filePath
>>> $1 = (const string &) @0x7fff43730500: {static npos = 
>>> 18446744073709551615,
>>>  _M_dataplus = {<std::allocator<char>> = 
>>> {<__gnu_cxx::new_allocator<char>> = {<No data fields>}, <No data 
>>> fields>}, _M_p = 0x6ca7e078 "/tmp/dskbuff--IpMvxN"}}
>>> (gdb) step
>>> 52        system(cmd);
>>> (gdb) step
>>> prof_handle_tick (signum=27) at mercury_prof.c:199
>>> 199     mercury_prof.c: No such file or directory.
>>>        in mercury_prof.c
>>> Current language:  auto; currently c
>>> (gdb) step
>>> 207     in mercury_prof.c
>>> (gdb) step
>>> 213     in mercury_prof.c
>>> (gdb) finish
>>> Run till exit from #0  prof_handle_tick (signum=27) at 
>>> mercury_prof.c:223
>>> <signal handler called>
>>> (gdb) step
>>> Single stepping until exit from function __restore_rt,
>>> which has no line number information.
>>> 0x00000037a6d3ac50 in system () from /lib64/libc.so.6
>>> (gdb) step
>>> Single stepping until exit from function system,
>>> which has no line number information.
>>> 0x00000037a6d3a7f0 in do_system () from /lib64/libc.so.6
>>> (gdb) step
>>> Single stepping until exit from function do_system,
>>> which has no line number information.
>>> <hangs forever>
>>>
>>> Any ideas whose fault is this? Any secure means to prevent that?
>>>
>>
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