Jean-Daniel Cryans created HBASE-7700:
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Summary: TestColumnSeeking is mathematically bound to fail
Key: HBASE-7700
URL: https://issues.apache.org/jira/browse/HBASE-7700
Project: HBase
Issue Type: Bug
Affects Versions: 0.94.4, 0.96.0
Reporter: Jean-Daniel Cryans
Assignee: Jean-Daniel Cryans
Fix For: 0.96.0, 0.94.5
First I'd like to say that TestColumnSeeking is a bad test. It's not
documented, it's non-deterministic, it's 2 methods with almost the same code.
So in each test it populates column lists this way:
{code}
for (int i = 0; i < numberOfTests; i++) {
kvMaps[i] = new HashMap<String, KeyValue>();
columnLists[i] = new ArrayList<String>();
for (String column : allColumns) {
if (Math.random() < selectPercent) {
columnLists[i].add(column);
}
}
}
{code}
Since selectPercent is 50% and there are 10 columns, there's something like a
1/1024 chance that one of the column list ends up with 0 column. This is later
mismanaged in the checks. First something like this will be printed out:
bq. 2013-01-28 11:50:02,200 INFO [pool-1-thread-1]
regionserver.TestColumnSeeking(140): Columns: 0 Keys: 0
Like it says, there's 0 columns so it couldn't add data. But then it still
makes sure later that the data is there with this check:
{code}
assertEquals(kvSet.size(), results.size());
{code}
Do notice that the parameters are reversed, and here the results.size() will be
0 since there are 0 columns for this test.
I see multiple ways to fix this:
- Skip tests that have 0 columns
- Change the randomness to at least have 1 column (like select 1 + 0..9
columns)
- Redo the whole unit test to not rely on randomness
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