covoar SIGKILL Investigation

Joel Sherrill joel at
Tue Aug 14 14:47:01 UTC 2018


There has been a thread offlist as we have been attempting to resolve
some issues that popped up using covoar at scale with Vijay's and
Chris' recent work. It appears that the magic number is 400 executables
which can be processed before covoar dies with a SIGKILL. This
should indicate that it has hit a hard limit.

We have tried using ulimit to limit things. I have no idea where
exceeding limits in a process is logged. Knowing that would be
very useful if someone can point us to the right place.

My current suspicion is that we have hit a maximum open
files limit. I don't recall when opened and
closed files before but if the DWARF support includes an open
file descriptor, then there is one left open for the entire duration
of the program run. The instance of executable information for
each executable exists for the entire program run. It wouldn't
hurt if we could close the DWARF helper file descriptor when
we have gathered all the information.

I am hoping gcov processing is turned off for Vijay's current
runs since that would add more open file descriptors.

I could be completely wrong on the limit being hit and am
open to ideas on how to figure out which one it is.

Vijay.. running valgrind on a run of covoar with only one
RTEMS executable would be a good start at figuring
out if there are resources allocated that could be freed
along the execution. As Chris has pointed out to me
before, I didn't really care much about clean up because
when the program ended, all the memory was freed anyway.
This is OK until you hit some limit.

Ideas appreciated on how to debug this enough to find
the cause.


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