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https://issues.apache.org/jira/browse/HBASE-4712?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13153539#comment-13153539
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nkeywal commented on HBASE-4712:
--------------------------------
New proposal:
1) Running tests
HBase tests are divided in three categories: small, medium and large, with
corresponding JUnit categories: SmallTests, MediumTests, LargeTests.
- Small tests are executed in a shared JVM. We put in this category all the
tests that can be executed quickly (the maximum execution time for a test is 15
seconds and they do not use a cluster) in a shared jvm.
- Medium tests represents tests that must be executed before proposing a patch.
They are designed to run in less than 30 minutes altogether, and are quite
stable in their results. They're designed to less than 50 seconds. They can use
a cluster, and each of them are executed in a separate JVM.
- Large tests are everything else. They are typically integration tests,
regression tests for specific bugs, timeout tests, performance tests. Some of
them can be flaky. They are executed before a commit on the pre-integration
machines. They can be run on the developper as well.
Commands are:
- mvn test - execute all tests in a separate JVM. All results
are presented in a single report.
- mvn -P runDevTests - execute small tests in a single JVM and medium
tests in separates jvm. There are two reports.
- mvn -P runAllTests - execute small tests in a single JVM and medium and
large tests in separates jvm. There are two reports, one for small, one for
medium and large.
- mvn -P runSmallTests - execute small tests in a single JVM.
It's as well possible to use the script 'hbasetests.sh'. This script runs the
medium and large tests in parallel with two maven instances, and provide a
single report. It must be executed from the directory which contains the
pom.xml. Commands are:
./dev-support/hbasetests.sh - execute small and medium tests
./dev-support/hbasetests.sh runAllTests - execute all tests
./dev-support/hbasetests.sh replayFailed - rerun the failed tests a second
time, in a separate jvm and without parallelisation.
2) Writing tests
Tests rules & hints are:
- As most as possible, tests should be written as small tests.
- All tests must be written to support parallel execution on the same machine,
hence should not use shared resources as fixed ports or fixed file names.
- Tests should not overlog. More than 100 lines/second makes the logs complex
to read and use i/o that are hence not available for the other tests.
- Tests can be written with HBaseTestingUtility . This class offers helper
functions to create a temp directory and do the cleanup, or to start a cluster.
- Categories and executin time
- All tests must be categorized, if not they could be skipped.
- All tests should be written to be as fast as possible.
- Small tests should last less than 15 seconds, and must not have any side
effect.
- Medium tests should last less than 45 seconds.
- large tests should last less than 3 minutes, this ensure a good
parallelisation for the ones using it, and ease the analysis when the test
fails.
- Sleeps:
- Whenever possible, tests should not use sleep, but rather waiting for the
real event. This is faster and clearer for the reader.
- Tests should not do a 'Thread.sleep' without testing an ending condition.
This allows understanding what the test is waiting for. Moreover, the test will
work whatever the machine performances.
- Sleep should be minimal to be as fast as possible. Waiting for a variable
should be done in a 40ms sleep loop. Waiting for a socket operation should be
done in a 200 ms sleep loop.
- Tests using cluster:
- Tests using a HRegion do not have to start a cluster: A region can use
the local file system.
- Start/stopping a cluster cost around 10 seconds. They should not be
started per test method but per class.
- Started cluster must be shutdown using
HBaseTestingUtility#shutdownMiniCluster, which cleans the directories.
- As most as possible, tests should use the default settings for the
cluster. When they don't, they should document it. This will allow to share the
cluster later.
@committers: Please tell me where I should put this, I will put it as a patch
(with the new comments taken into account of course!)
> Document rules for writing tests
> --------------------------------
>
> Key: HBASE-4712
> URL: https://issues.apache.org/jira/browse/HBASE-4712
> Project: HBase
> Issue Type: Task
> Components: test
> Affects Versions: 0.92.0
> Reporter: nkeywal
> Assignee: nkeywal
> Priority: Minor
>
> We saw that some tests could be improved. Documenting the general rules could
> help.
> Proposal:
> HBase tests are divided in three categories: small, medium and large, with
> corresponding JUnit categories: SmallTest, MediumTest, LargeTest
> Small tests are executed in parallel in a shared JVM. They must last less
> than 15 seconds. They must NOT use a cluster.
> Medium tests are executed in separate JVM. They must last less than 50
> seconds. They can use a cluster. They must not fail occasionally.
> Small and medium tests must not need more than 30 minutes to run altogether.
> Small and medium tests should be executed by the developers before submitting
> a patch.
> Large tests are everything else. They are typically integration tests,
> non-regression tests for specific bugs, timeout tests, performance tests.
> Tests rules & hints are:
> - As most as possible, tests should be written as small tests.
> - All tests should be written to support parallel execution on the same
> machine, hence should not use shared resources as fixed ports or fixed file
> names.
> - All tests should be written to be as fast as possible.
> - Tests should not overlog. More than 100 lines/second makes the logs complex
> to read and use i/o that are hence not available for the other tests.
> - Tests can be written with HBaseTestingUtility . This class offers helper
> function to create a temp directory and do the cleanup, or to start a cluster.
> - Sleeps:
> - Tests should not do a 'Thread.sleep' without testing an ending
> condition. This allows understanding what the test is waiting for. Moreover,
> the test will work whatever the machine performances.
> - Sleep should be minimal to be as fast as possible. Waiting for a
> variable should be done in a 40ms sleep loop. Waiting for a socket operation
> should be done in a 200 ms sleep loop.
> - Tests using cluster:
> - Tests using a HRegion do not have to start a cluster: A region can use
> the local file system.
> - Start/stopping a cluster cost around 10 seconds. They should not be
> started per test method but per class.
> - Started cluster must be shutdown using
> HBaseTestingUtility#shutdownMiniCluster, which cleans the directories.
> - As most as possible, tests should use the default settings for the
> cluster. When they don't, they should document it. This will allow to share
> the cluster later.
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