TFile problem with TThread?!

ROOT
1

Hi everyone,

I got a problem with a TFile object during running my root application. The setup of my application looks like this:

  • got a main method which provide global data containing a TFile object
  • global data is protected with a TSemaphore
  • the main method starts two TTreads
  • a gui thread with a start and a stop button for the “work thread”
  • the work thread is running fine when I push the start button
  • but when I push the stop button, which just set a start/stop flag for the working thread in the global data. My working thread stops at points like TFile::Write() or TFile::Get(), which has nothing to do with my stop mechanic .

Now I try to create a example program to show you the error but this already stops when creating a new TFile?

Someone got an idea what I’m doing wrong?

Cheers
Benni

2

[quote]Someone got an idea what I’m doing wrong?[/quote]Not really, this looks fine on the surface. What are the stack trace of where the thread unexpectedly stop?

Philippe.

3

Hi Philippe,

here the stack trace of my program:

Obtained 6 stack frames.
rootAnalyser(_ZN17TControlFunctions12SaveRootFileEv+0x59) [0x8074f2f]
rootAnalyser(_ZN13TExtraction5StartEv+0xfc) [0x806e8ec]
rootAnalyser(_Z12startExtractPv+0x50) [0x8056b48]
/opt/root/lib/libThread.so(_ZN7TThread8FunctionEPv+0x8d) [0x41dc0c9d]
/lib/libpthread.so.0 [0x4259bc60]
/lib/libc.so.6(__clone+0x57) [0x426c7b77]

Hope it’s useful and enough? Never create my own stack trace output before.

Cheers

Benni

4

Hi,

The stack trace seems to indicate that the crash is in your code, could the problem be there?

Philippe.

5

Hi,

of course the problem could be in my code, but I and two associates didn’t find anything?!? That is why I post the topic here.

What hints can I get out of the stack trace? It’s a little bit cryptic to me.

Benni

6

Hi,

I recommend you try running your example under gdb. I.e. if you start you example with./mycode 123 abcdogdb --args ./mycode 123 abc gdb> run .... segfault appears ... gdb> where which (especially if you build your code with the -g option) would give you the line number where the crash happens. The stack trace you gave says that the crash happened in the routine:echo _ZN17TControlFunctions12SaveRootFileEv | c++filt TControlFunctions::SaveRootFile()

Cheers,
Philippe.

7

Hi,
I rebuild my project a little bit, because I thought I had a problem in my program structure. Now my TFile object is created in the thread, which use it exclusive. No other thread is now using the object.

Now when I first start my program after a reboot of the system I get the segmentation violation below, when I start the program a second time it is running “fine”, except of my old problem.

Do I handle the TFile object wrong?

Cheers
Benni

8

Why are my attachments not added??
segmentation violation.txt (4.97 KB)
Class InitRootFile.txt (2.66 KB)

9

[quote]Why are my attachments not added??[/quote]No sure, it might have a ‘dangerous’ extension or it might be too large. One way around both is to place your code on a web server (or on afs) where we can download it.

[quote]Do I handle the TFile object wrong?[/quote]No idea :slight_smile: We would need to see your code. You might also see the problem by running your case under valgrind (see valgrind.org).

Cheers,
Philippe.

10

I took a older version of my program and add step by step the new parts until my current version.

The last version which work has the following construction:

  • parent thread which creates:
  • the working thread
  • and a thread for a text menu

Next step was to change the text menu by a GUI with the same functions (start/stop the working thread). Here occurs the problems which I described in my first posed.

I will throw out the code parts which are not necessary and post the code later today or tomorrow. And thanks for the valgrind hint, I will try it.

EDIT Code added.

  • in globalDef.h the different versions can be set on/off
  • the error occurs when using TControlFunctions::InitParamTable() without TFile::Write() works fine
  • with TControlFunctions::InitParamTable() it crashes when I want to stop the program
    EDIT

Cheers
Benni
rootTmAnalyser_v0.2_rebuild.tar.gz (9.83 KB)

11

Hi,

For me your example fails with:[quote]Error in TMySQLServer::TMySQLServer: Code: 2002 Msg: Can’t connect to local MySQL server through socket ‘/var/lib/mysql/mysql.sock’ (2)

  • ERROR: Can not connect to the MySql server[/quote]

Cheers,
Philippe.

12

Oh sry, forget to take out the mySQL functions. Replaced it with dummys.
rootTmAnalyser_v0.2_rebuild_1.tar.gz (9.2 KB)

13

Hi,

Please note the following C++ syntax errors: TControlFunctions.h:43: error: extra qualification ‘TControlFunctions::’ on member ‘Init’ TControlFunctions.h:44: error: extra qualification ‘TControlFunctions::’ on member ‘SaveRootFile’ TControlFunctions.h:63: error: extra qualification ‘TControlFunctions::’ on member ‘InitRootFile’ TControlFunctions.h:64: error: extra qualification ‘TControlFunctions::’ on member ‘InitParamTable’

Philippe.

14

Hi,

I was able to compile and run the code, but I fail to make it crash. Can you remind which exact setting I need to use and which exact step I need to take to get to the crash?

Thanks,
Philippe.

15

Hi Philippe,

Set

#define FUNTIONAL_VERSION_1 0
#define FUNTIONAL_VERSION_2 0

in globalDef.h. Program should crash when pushing stopbutton.
When it not does could it be because I use root v5.24?

Cheers
Benni

16

Hi,

I can’t reproduce the problem with the trunk.

[quote]When it not does could it be because I use root v5.24?[/quote]Can you try with the trunk or at least v5.27/06?

Cheers,
Philippe.

17

Hi,

I try to install the new root version, but make stops with:

XrdPosixXrootd.cc: In static member function static int XrdPosixXrootd::Statfs(const char*, statfs*)': XrdPosixXrootd.cc:1210: error: 'struct statfs' has no member named 'f_frsize' make[5]: *** [../../obj/XrdPosixXrootd.o] Fehler 1 make[4]: *** [Linuxall] Fehler 2 make[3]: *** [all] Fehler 2 make[2]: *** [XrdPosix] Fehler 2 make[1]: *** [all] Fehler 2 make[1]: Leaving directory/opt/root_v5.27.06/net/xrootd/src/xrootd’
*** Error condition reported by make (rc = 2):
make: *** [net/xrootd/src/xrootd/LastBuild.d] Fehler 1
rm core/utils/src/RStl_tmp.cxx core/utils/src/rootcint_tmp.cxx

18

[quote]I try to install the new root version,[/quote]On which platform/compiler? Can you try the trunk?
Alternatively, if you do not need xrootd, disable it for now (configure … --disable-xrootd …)

Cheers,
Philippe.

19

Good morning Philippe,

  • I’m working with suse Linux 8.2 (can’t use a newer Linux because of company software which only works with the old kernel) and the GNU C++ compiler (3.3-23)

  • same failure with the trunk

  • was able to install root v5.27.06 with the option, but no effect :frowning: same as before.

Cheers
Benni

20

Hi,

nobody any new ideas so fare?

I thought about another thing which might cause the problem:

Could it be that a TFile object of one thread has problems to work when in another thread (GUI) a polling loop like this below is running:

do{ // wait until other thread is finished
semaphore->Wait();
OTHER_THREAD_IS_DOING_FLAG = globalData.OTHER_THREAD_IS_DOING_FLAG;
semaphore->Post();
sleep(1);
}while(OTHER_THREAD_IS_DOING_FLAG != THREAD_DO_IDLE);

Cheers,
Benni