std::ofstream constructor blocking - c++

Question

I have the following code:
std::ofstream stat("/opt/lic_status");
if ( stat.is_open() )
{
stat << ver;
stat.close();
}
My problem is that on the first line the execution is blocked. A coredump was generated by a watchdog during this block and it looks like this:
(gdb) bt
#0 0x00cb5430 in __kernel_vsyscall ()
#1 0x00b2833b in open () from /lib/libc.so.6
#2 0x00ac37c8 in _IO_new_file_fopen () from /lib/libc.so.6
#3 0x00ab73dd in __fopen_internal () from /lib/libc.so.6
#4 0x00ab9c4c in fopen64 () from /lib/libc.so.6
#5 0x00d6e877 in std::__basic_file<char>::open(char const*, std::_Ios_Openmode, int) () from /usr/lib/libstdc++.so.6
#6 0x00d1d75e in std::basic_filebuf<char, std::char_traits<char> >::open(char const*, std::_Ios_Openmode) () from /usr/lib/libstdc++.so.6
#7 0x08b625b8 in open () at /usr/lib/gcc/i686-redhat-linux/4.4.4/../../../../include /c++/4.4.4/fstream:699
#8 basic_ofstream () at /usr/lib/gcc/i686-redhat-linux/4.4.4/../../../../include/c++/4.4.4/fstream:628
I need to mention that I don't know what was the state of the /opt/lic_status file when the problem occurred. I don't know if it was opened by other process or even if it existed at all.
Does anoyone have any suggestion on what could have caused this?
I only have the coredump, can I get any info out of it?

Answer 1

"I need to mention that I don't know what was the state of the
/opt/lic_status file when the problem occurred. I don't know if it was opened by other process or even if it existed at all."
Based on my understanding none of the above attribute/state of the file can lead the program to block on that particular line(.i.e. where user mode program is calling open() inside the std::ofstream constructor). Whenever user mode program calls open() system call to open the files, system would complete the call with appropriate error code. It will not be the case that system(kernel mode) would not return back to user mode.
Does anyone have any suggestion on what could have caused this? I
only have the coredump, can I get any info out of it?
Entire system(kernel) is not in good state(due to some unknown reason).
The program is multi threaded and some other threads has been stuck somewhere. By looking the call stack of this thread it looks OK as it is executing in the kernel mode and calling open() system call.
If we are experiencing the first case, then I believe we can not do much and core-dump file of the program would not give any extra information to identify/confirm this. Core-dump file just contains the snapshot of that particular process.
However, if we are in second case, then we should try to analyze core-dump file further. We can fire following commands in GDB command prompt once core-dump file is loaded.
$info threads
$thread apply all backtrace
The above command would give the information (if your program is multi-threaded) as well call stack of all threads. This might be helpful to understand your problem. You can ignore the above information if you have already done it.