linux-kernel - [BUG] perf stat: hangs with -p and process completes

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Date:   Fri, 12 Oct 2018 14:26:09 -0700
From:   Stephane Eranian <eranian@...gle.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [BUG] perf stat: hangs with -p and process completes

Hi,

I am running into a perf stat issue with the -p option which allows you
to attach to a running process. If that process happens to terminate
while under monitoring
perf hangs in there and never terminates. The proper behavior would be to stop.
I can see the issue in that the attached process is not a child, so
wait() would not work.

To reproduce:
  $ sleep 10 &
  $ perf stat -p $!

doing the same with perf record works, so there is a solution to this problem.