Online program crashes on TMapFile (shared histograms)

[rayad]

---

ROOT Version: v5.34.32
Platform: Ubuntu 12.04.5 LTS (Precise)

---

Dear All, I am using the shared histograms utility TMapFile and my online programs was working for years but it is crashing now. Here how I call TMapFile:

(I note here that I know we are using an old version of ROOT (v5.34.32) and also old version of ubuntu (12.04.5) and we should because else some parts of the online code will not as set by others to work with that version.)

TMapFile *labmhistfile; // global variable
{
.
.
.
sprintf(line,"%s/labmhistshared/plots/labmhist.map",motherpath);
   labmhistfile = TMapFile::Create(line,"RECREATE", 50000000,
                            "LABM shared histograms");
.
.
.
}

Then in a different process:

{
extern TMapFile *labmhistfile;
..
..
..
..
labmhistfile->Update(); // it crashes here as listed below in the log file.
..
..
..
..
}

******************* Log file *************

*** Break *** segmentation violation
New day: 12-Feb-2019 
 Create Histograms 



===========================================================
There was a crash.
This is the entire stack trace of all threads:
===========================================================
#0  0x00007f3cb2a1dcae in waitpid () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007f3cb29a3f4e in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#2  0x00007f3cb49ac267 in TUnixSystem::StackTrace() () from /home/labm/root/pro/lib/libCore.so
#3  0x00007f3cb49aebc3 in TUnixSystem::DispatchSignals(ESignals) () from /home/labm/root/pro/lib/libCore.so
#4  <signal handler called>
#5  0x00007f3cb4306214 in TMapFile::Update(TObject*) () from /home/labm/root/pro/lib/libRIO.so
#6  0x000000000040312a in fillhistshared () at fill_hist_shared.cc:213
#7  0x00000000004039c7 in main () at main.cc:61
===========================================================


The lines below might hint at the cause of the crash.
If they do not help you then please submit a bug report at
http://root.cern.ch/bugs. Please post the ENTIRE stack trace
from above as an attachment in addition to anything else
that might help us fixing this issue.
===========================================================
#5  0x00007f3cb4306214 in TMapFile::Update(TObject*) () from /home/labm/root/pro/lib/libRIO.so
#6  0x000000000040312a in fillhistshared () at fill_hist_shared.cc:213
#7  0x00000000004039c7 in main () at main.cc:61
===========================================================

So it crashes at TMapFile::Update , so maybe the root shared histograms “labmhistfile” with TMapFile is not well returned by TMapFile?

Thank you, Rachid

[Axel]

Hi Rachid,

we should because else some parts of the online code will not as set by others to work with that version

I don’t think any experiment should be using Ubuntu 12 for DAQ purposes; I don’t see a reason for not updating. Software needs maintenance. You will run into problems with old software not supporting current hardware at some point; expertise and willingness to deal with bugs (that have likely since been fixed) decreases over time. That’s not just true for ROOT, that’s true for any software project - even Ubuntu.

You said it was working for years - what has changed since?

Axel.

[rayad]

I don’t think any experiment should be using Ubuntu 12 for DAQ purposes; I don’t see a reason for not
updating. Software needs maintenance. You will run into problems with old software not supporting current >hardware at some point; expertise and willingness to deal with bugs (that have likely since been fixed) >decreases over time. That’s not just true for ROOT, that’s true for any software project - even Ubuntu.

As I said is not coming from me because we are using some programs (part of the DAQ) that are done by others and need this version of ubuntu (they are binary) and no manpower to update them. For my part of the DAQ I wrote(most of it) I used it with higher version of ubuntu (latest one) and it is working well.

You said it was working for years - what has changed since?
No changes at all.

Maybe we can start debugging at least printing what TMapFile returns: so should I tested that it should not a NULL pointer or …?

Rachid