Test SIGTERM vs ~TFile

[Axel-Naumann]

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Description

Rumors have it that SIGTERM doesn't trigger writing in-memory objects to open TFiles. We should have a test for this.

Reproducer

Likely this should be enough:

TFile file("out.root", "RECREATE");
TH1F hist("h", "h", 10, 0., 1.);
raise(SIGTERM);

ROOT version

6.29/01

Installation method

From source

Operating system

Some Linux

Additional context

No response

[Axel-Naumann]

It might be that this bug requires the object to be in a sub-TDirectory:

TFile file("out.root", "RECREATE");
file.mkdir("subdir")->cd();
TH1F hist("h", "h", 10, 0., 1.);
raise(SIGTERM);

[ferdymercury]

If we add this in TerminalConfigUnix.cpp, then both examples are fixed.

#include "TROOT.h"
#include "TMethodCall.h"

if (signum==SIGTERM) { // SIGTERM is a gentle way of exiting, so it should auto-save open files
// TO-DO this could be moved to gROOT->CleanupOnSigterm();
if (gROOT) {
     R__LOCKGUARD(gROOTMutex);

     if (gROOT->GetListOfFiles()) {
        TIter next(gROOT->GetListOfFiles());
        TObject* obj = nullptr;
        while((obj = (TObject*)next())) {
           if (obj) {
              TMethodCall call1(obj->IsA(), "Write", "");
              TMethodCall call2(obj->IsA(), "Close", "");
              call1.Execute((void *)(obj));
              call2.Execute((void *)(obj));
           }
        }
     }
  gROOT->GetListOfFiles()->Delete("slow");
  }
      if (gROOT->GetListOfSockets())
         gROOT->GetListOfSockets()->Delete();
      if (gROOT->GetListOfMappedFiles())
         gROOT->GetListOfMappedFiles()->Delete("slow");
      if (gROOT->GetListOfClosedObjects())
         gROOT->GetListOfClosedObjects()->Delete("slow");
}
  signal(signum, SIG_DFL); // unregister ourselves

[pcanal]

It might be that this bug requires the object to be in a sub-TDirectory:

Is there really a difference between the 2 cases?

Rumors have it that SIGTERM doesn't trigger writing in-memory objects to open TFiles.

It is debatable whether this is the desired behavior or not. We do not know whether the user sent a SIGTERM to 'prevent' the process for doing any more 'damage' to the file or whether they expected TFile to behave as a google doc with an auto-save features.

The best/most we should do is make sure the file is 'properly' closed via the execution of TROOT::CloseFiles.

[ferdymercury]

It is debatable whether this is the desired behavior or not. We do not know whether the user sent a SIGTERM to 'prevent' the process for doing any more 'damage'

Wouldn't the user send then a SIGKILL instead ?

[pcanal]

Wouldn't the user send then a SIGKILL instead ?

That is a good question.