Hello David Ribeiro Alves, Mike Percy,

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to review the following change.

Change subject: Fix stray memory writes due to tcmalloc profiling

Fix stray memory writes due to tcmalloc profiling

This fixes an issue that has been causing frequent crashes in
JD.com's production cluster as well as various Cloudera test clusters.
The crashes would be in various different places, but the key signature
was that offset 120 in some data structure or array (eg the 16th element
of a vector) would be corrupted.

After doing a git bisect using an integration testing cluster running
an ITBLL workload, I found that this was a regression caused by the
introduction of tcmalloc contention profiling[1]. The short explanation
is that, if we experienced contention while freeing a Trace object, we
could in some cases increment offset 120 of some other allocation
which occurred soon after the deallocation of the Trace.

The issue is described in more detail in a new comment in trace.h.

With this patch, I was unable to reproduce the issue on the test
cluster. No new test is added since this is quite timing-dependent
and not amenable to unit testing or even stress testing.

[1] commit f6691e744b9cb796e1bbc6e07953f21f387c9a88

Change-Id: I9afca83d9cc24585960f6bf68d8996c4736ce6cb
M src/kudu/util/trace.h
1 file changed, 23 insertions(+), 3 deletions(-)

  git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/45/3445/1
To view, visit http://gerrit.cloudera.org:8080/3445
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I9afca83d9cc24585960f6bf68d8996c4736ce6cb
Gerrit-PatchSet: 1
Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-Owner: Todd Lipcon <t...@apache.org>
Gerrit-Reviewer: David Ribeiro Alves <dral...@apache.org>
Gerrit-Reviewer: Mike Percy <mpe...@apache.org>

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