Hello Kudu Jenkins,

I'd like you to reexamine a change.  Please visit

    http://gerrit.cloudera.org:8080/4446

to look at the new patch set (#6).

Change subject: [tests] fix test which fails with two cpus and document other 
dependencies
......................................................................

[tests] fix test which fails with two cpus and document other dependencies

Various tests fail due to lack of lsof and low resource
limits, which are not documented.

CodegenTest.TestCodeCache - fails on my two cpu host, t2.large
increasing the cache size resolves this failure. The test is
depending on:

1) key skew in the SharedLRUCache to obtain hits
2) the fact that capacity of SharedLRUCache is higher than the capacity
configured if the configured capacity is not divisible by the the number
of CPUs.

For example, the capacity is set here:

  FLAGS_codegen_cache_capacity = 10;

However, if the capacity is not perfectly divisible by the number of CPUs,
actual capacity is slightly higher.

CPU 2 => Capacity 10, 5/shard
CPU 4 => Capacity 12, 3/shard
CPU 8 => Capacity 16, 2/shard

Due to this calculation:

const size_t per_shard = (capacity + (num_shards - 1)) / num_shards;

Additionally, the test depends on key skew. For example, I added some temporary
logging which logged each insert. Let's look at inserts into shard 0. Under the
4 CPU case, where each shard has a capacity of 3, shard 3 only sees three 
inserts
in pass 0 resulting in hits on the next pass:

pass: 0
Insert: hash = 460595995, shard = 0
Insert: hash = 339190469, shard = 0
Insert: hash = 326003543, shard = 0
pass: 1

Under the two CPU case, both shard's see more than 5 inserts, causing no cache 
hits.

pass: 0
Insert: hash = 1886151623, shard = 0
Insert: hash = 1395239506, shard = 0
Insert: hash = 1931154674, shard = 0
Insert: hash = 460595995, shard = 0
Insert: hash = 1440596256, shard = 0
Insert: hash = 1870227699, shard = 0
Insert: hash = 1163308785, shard = 0
Insert: hash = 1980547462, shard = 0
Insert: hash = 1106104592, shard = 0
Insert: hash = 1702846352, shard = 0
Insert: hash = 1230845174, shard = 0
Insert: hash = 1903296752, shard = 0
Insert: hash = 1395526688, shard = 0
Insert: hash = 339190469, shard = 0
Insert: hash = 1540160781, shard = 0
Insert: hash = 1377131543, shard = 0
Insert: hash = 2125989246, shard = 0
Insert: hash = 326003543, shard = 0
pass: 1
Insert: hash = 1886151623, shard = 0
Insert: hash = 1395239506, shard = 0
Insert: hash = 1931154674, shard = 0
Insert: hash = 460595995, shard = 0
Insert: hash = 1440596256, shard = 0
Insert: hash = 1870227699, shard = 0
Insert: hash = 1163308785, shard = 0
Insert: hash = 1980547462, shard = 0
Insert: hash = 1106104592, shard = 0
Insert: hash = 1702846352, shard = 0
Insert: hash = 1230845174, shard = 0
Insert: hash = 1903296752, shard = 0
Insert: hash = 1395526688, shard = 0
Insert: hash = 339190469, shard = 0
Insert: hash = 1540160781, shard = 0
Insert: hash = 1377131543, shard = 0
Insert: hash = 2125989246, shard = 0
Insert: hash = 326003543, shard = 0

AFAICT increasing the capacity of the cache doesn't impact correctness.

Change-Id: I81b70f63923078d449f6541a61b292517e49877d
---
M docs/installation.adoc
M src/kudu/codegen/codegen-test.cc
M src/kudu/gutil/sysinfo.cc
3 files changed, 11 insertions(+), 3 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/46/4446/6
-- 
To view, visit http://gerrit.cloudera.org:8080/4446
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I81b70f63923078d449f6541a61b292517e49877d
Gerrit-PatchSet: 6
Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-Owner: Brock Noland <br...@phdata.io>
Gerrit-Reviewer: Adar Dembo <a...@cloudera.com>
Gerrit-Reviewer: Brock Noland <br...@phdata.io>
Gerrit-Reviewer: Kudu Jenkins
Gerrit-Reviewer: Todd Lipcon <t...@apache.org>
Gerrit-Reviewer: Will Berkeley <wdberke...@gmail.com>

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