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revisit 17393 - changes made to artdaq/ArtModules/RootDAQOutput/RootDAQOut_module.cc #131

Closed eflumerf closed 2 years ago

eflumerf commented 2 years ago

This issue has been migrated from https://cdcvs.fnal.gov/redmine/issues/22116 (FNAL account required) Originally created by @ron003 on 2019-03-12 19:20:53

changes needed to be made to artdaq/ArtModules/RootDAQOutput/RootDAQOut_module.cc to support fileName /dev/null

eflumerf commented 2 years ago

Comment by @jcfreeman2 on 2019-03-13 17:29:43

The issue at hand is that having RootDAQOut's fileName set to "/dev/null" results in the art process printing out 

%MSG-s ArtException:  PostEndJob 13-Mar-2019 11:55:26 CDT ModuleEndJob
cet::exception caught in art
---- OtherArt BEGIN
  ---- FileOpenError BEGIN
    RootOutput cannot ascertain a unique temporary filename for output based on stem
    "/dev/RootDAQOut": Permission denied.
  ---- FileOpenError END

and then dying and relaunching (and dying again) multiple times during a run.

The fix was made by Ron and can be found on the artdaq branch 17393_artdaq_RootDAQOutput_dev_null_changes (HEAD is b188ed0c1f15e021f9edc7bf584c6d1d74b0fe0f)

eflumerf commented 2 years ago

Comment by @jcfreeman2 on 2019-03-13 17:36:59

To test the change, I modified the demo config at the head of the DAQInterface develop branch (319e3b192252190aa2f888c5b8108650fbe48531) so that RootDAQOut would write to /dev/null, i.e.:

   normalOutput: {
     module_type: RootDAQOut
-    fileName: "/tmp/artdaqdemo_r%06r_sr%02s_%to_%#.root"
-    fileProperties: { maxSubRuns: 1 maxRuns: 1  }
-    fastCloning: false
-    compressionLevel: 3
+    fileName: "/dev/null"
   }

and after witnessing the problem described above with run v3_04_00 (my run 2392 on mu2edaq01, see mu2edaq01:/home/jcfree/run_records/2392 for details), it appears to have gone away when using the 17393_artdaq_RootDAQOutput_dev_null_changes branch (see /home/jcfree/run_records/2394).