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% Testing the JDK


The bulk of JDK tests use jtreg, a regression test framework and test runner built for the JDK's specific needs. Other test frameworks are also used. The different test frameworks can be executed directly, but there is also a set of make targets intended to simplify the interface, and figure out how to run your tests for you.

Running tests locally with make test

This is the easiest way to get started. Assuming you've built the JDK locally, execute:

$ make test

This will run a default set of tests against the JDK, and present you with the results. make test is part of a family of test-related make targets which simplify running tests, because they invoke the various test frameworks for you. The "make test framework" is simple to start with, but more complex ad-hoc combination of tests is also possible. You can always invoke the test frameworks directly if you want even more control.

Some example command-lines:

$ make test-tier1
$ make test-jdk_lang JTREG="JOBS=8"
$ make test TEST=jdk_lang
$ make test-only TEST="gtest:LogTagSet gtest:LogTagSetDescriptions" GTEST="REPEAT=-1"
$ make test TEST="hotspot:hotspot_gc" JTREG="JOBS=1;TIMEOUT_FACTOR=8;JAVA_OPTIONS=-XshowSettings -Xlog:gc+ref=debug"
$ make test TEST="jtreg:test/hotspot:hotspot_gc test/hotspot/jtreg/native_sanity/"
$ make test TEST="micro:java.lang.reflect" MICRO="FORK=1;WARMUP_ITER=2"
$ make exploded-test TEST=tier2

"tier1" and "tier2" refer to tiered testing, see further down. "TEST" is a test selection argument which the make test framework will use to try to find the tests you want. It iterates over the available test frameworks, and if the test isn't present in one, it tries the next one. The main target test uses the jdk-image as the tested product. There is also an alternate target exploded-test that uses the exploded image instead. Not all tests will run successfully on the exploded image, but using this target can greatly improve rebuild times for certain workflows.

Previously, make test was used to invoke an old system for running tests, and make run-test was used for the new test framework. For backward compatibility with scripts and muscle memory, run-test and variants like exploded-run-test or run-test-tier1 are kept as aliases.


To be able to run JTReg tests, configure needs to know where to find the JTReg test framework. If it is not picked up automatically by configure, use the --with-jtreg=<path to jtreg home> option to point to the JTReg framework. Note that this option should point to the JTReg home, i.e. the top directory, containing lib/jtreg.jar etc. (An alternative is to set the JT_HOME environment variable to point to the JTReg home before running configure.)

To be able to run microbenchmarks, configure needs to know where to find the JMH dependency. Use --with-jmh=<path to JMH jars> to point to a directory containing the core JMH and transitive dependencies. The recommended dependencies can be retrieved by running sh make/devkit/, after which --with-jmh=build/jmh/jars should work.

When tests fail or timeout, jtreg runs its failure handler to capture necessary data from the system where the test was run. This data can then be used to analyze the test failures. Collecting this data involves running various commands (which are listed in files residing in test/failure_handler/src/share/conf) and some of these commands use sudo. If the system's sudoers file isn't configured to allow running these commands, then it can result in password being prompted during the failure handler execution. Typically, when running locally, collecting this additional data isn't always necessary. To disable running the failure handler, use --enable-jtreg-failure-handler=no when running configure. If, however, you want to let the failure handler to run and don't want to be prompted for sudo password, then you can configure your sudoers file appropriately. Please read the necessary documentation of your operating system to see how to do that; here we only show one possible way of doing that - edit the /etc/sudoers.d/sudoers file to include the following line:

johndoe ALL=(ALL) NOPASSWD: /sbin/dmesg

This line configures sudo to not prompt for password for the /sbin/dmesg command (this is one of the commands that is listed in the files at test/failure_handler/src/share/conf), for the user johndoe. Here johndoe is the user account under which the jtreg tests are run. Replace the username with a relevant user account of your system.

Test selection

All functionality is available using the test make target. In this use case, the test or tests to be executed is controlled using the TEST variable. To speed up subsequent test runs with no source code changes, test-only can be used instead, which do not depend on the source and test image build.

For some common top-level tests, direct make targets have been generated. This includes all JTReg test groups, the hotspot gtest, and custom tests (if present). This means that make test-tier1 is equivalent to make test TEST="tier1", but the latter is more tab-completion friendly. For more complex test runs, the test TEST="x" solution needs to be used.

The test specifications given in TEST is parsed into fully qualified test descriptors, which clearly and unambigously show which tests will be run. As an example, :tier1 will expand to jtreg:$(TOPDIR)/test/hotspot/jtreg:tier1 jtreg:$(TOPDIR)/test/jdk:tier1 jtreg:$(TOPDIR)/test/langtools:tier1 jtreg:$(TOPDIR)/test/nashorn:tier1 jtreg:$(TOPDIR)/test/jaxp:tier1. You can always submit a list of fully qualified test descriptors in the TEST variable if you want to shortcut the parser.

Common Test Groups

Ideally, all tests are run for every change but this may not be practical due to the limited testing resources, the scope of the change, etc.

The source tree currently defines a few common test groups in the relevant TEST.groups files. There are test groups that cover a specific component, for example hotspot_gc. It is a good idea to look into TEST.groups files to get a sense what tests are relevant to a particular JDK component.

Component-specific tests may miss some unintended consequences of a change, so other tests should also be run. Again, it might be impractical to run all tests, and therefore tiered test groups exist. Tiered test groups are not component-specific, but rather cover the significant parts of the entire JDK.

Multiple tiers allow balancing test coverage and testing costs. Lower test tiers are supposed to contain the simpler, quicker and more stable tests. Higher tiers are supposed to contain progressively more thorough, slower, and sometimes less stable tests, or the tests that require special configuration.

Contributors are expected to run the tests for the areas that are changed, and the first N tiers they can afford to run, but at least tier1.

A brief description of the tiered test groups:

  • tier1: This is the lowest test tier. Multiple developers run these tests every day. Because of the widespread use, the tests in tier1 are carefully selected and optimized to run fast, and to run in the most stable manner. The test failures in tier1 are usually followed up on quickly, either with fixes, or adding relevant tests to problem list. GitHub Actions workflows, if enabled, run tier1 tests.

  • tier2: This test group covers even more ground. These contain, among other things, tests that either run for too long to be at tier1, or may require special configuration, or tests that are less stable, or cover the broader range of non-core JVM and JDK features/components(for example, XML).

  • tier3: This test group includes more stressful tests, the tests for corner cases not covered by previous tiers, plus the tests that require GUIs. As such, this suite should either be run with low concurrency (TEST_JOBS=1), or without headful tests(JTREG_KEYWORDS=\!headful), or both.

  • tier4: This test group includes every other test not covered by previous tiers. It includes, for example, vmTestbase suites for Hotspot, which run for many hours even on large machines. It also runs GUI tests, so the same TEST_JOBS and JTREG_KEYWORDS caveats apply.


JTReg tests can be selected either by picking a JTReg test group, or a selection of files or directories containing JTReg tests. Documentation can be found at, note especially the extensive FAQ.

JTReg test groups can be specified either without a test root, e.g. :tier1 (or tier1, the initial colon is optional), or with, e.g. hotspot:tier1, test/jdk:jdk_util or $(TOPDIR)/test/hotspot/jtreg:hotspot_all. The test root can be specified either as an absolute path, or a path relative to the JDK top directory, or the test directory. For simplicity, the hotspot JTReg test root, which really is hotspot/jtreg can be abbreviated as just hotspot.

When specified without a test root, all matching groups from all test roots will be added. Otherwise, only the group from the specified test root will be added.

Individual JTReg tests or directories containing JTReg tests can also be specified, like test/hotspot/jtreg/native_sanity/ or hotspot/jtreg/native_sanity. Just like for test root selection, you can either specify an absolute path (which can even point to JTReg tests outside the source tree), or a path relative to either the JDK top directory or the test directory. hotspot can be used as an alias for hotspot/jtreg here as well.

As long as the test groups or test paths can be uniquely resolved, you do not need to enter the jtreg: prefix. If this is not possible, or if you want to use a fully qualified test descriptor, add jtreg:, e.g. jtreg:test/hotspot/jtreg/native_sanity.


Note: To be able to run the Gtest suite, you need to configure your build to be able to find a proper version of the gtest source. For details, see the section "Running Tests" in the build documentation.

Since the Hotspot Gtest suite is so quick, the default is to run all tests. This is specified by just gtest, or as a fully qualified test descriptor gtest:all.

If you want, you can single out an individual test or a group of tests, for instance gtest:LogDecorations or gtest:LogDecorations.level_test_vm. This can be particularly useful if you want to run a shaky test repeatedly.

For Gtest, there is a separate test suite for each JVM variant. The JVM variant is defined by adding /<variant> to the test descriptor, e.g. gtest:Log/client. If you specify no variant, gtest will run once for each JVM variant present (e.g. server, client). So if you only have the server JVM present, then gtest:all will be equivalent to gtest:all/server.


Which microbenchmarks to run is selected using a regular expression following the micro: test descriptor, e.g., micro:java.lang.reflect. This delegates the test selection to JMH, meaning package name, class name and even benchmark method names can be used to select tests.

Using special characters like | in the regular expression is possible, but needs to be escaped multiple times: micro:ArrayCopy\\\\\|reflect.

Special tests

A handful of odd tests that are not covered by any other testing framework are accessible using the special: test descriptor. Currently, this includes failure-handler and make.

  • Failure handler testing is run using special:failure-handler or just failure-handler as test descriptor.

  • Tests for the build system, including both makefiles and related functionality, is run using special:make or just make as test descriptor. This is equivalent to special:make:all.

    A specific make test can be run by supplying it as argument, e.g. special:make:idea. As a special syntax, this can also be expressed as make-idea, which allows for command lines as make test-make-idea.

Test results and summary

At the end of the test run, a summary of all tests run will be presented. This will have a consistent look, regardless of what test suites were used. This is a sample summary:

Test summary
   TEST                                          TOTAL  PASS  FAIL ERROR
>> jtreg:jdk/test:tier1                           1867  1865     2     0 <<
   jtreg:langtools/test:tier1                     4711  4711     0     0
   jtreg:nashorn/test:tier1                        133   133     0     0

Tests where the number of TOTAL tests does not equal the number of PASSed tests will be considered a test failure. These are marked with the >> ... << marker for easy identification.

The classification of non-passed tests differs a bit between test suites. In the summary, ERROR is used as a catch-all for tests that neither passed nor are classified as failed by the framework. This might indicate test framework error, timeout or other problems.

In case of test failures, make test will exit with a non-zero exit value.

All tests have their result stored in build/$BUILD/test-results/$TEST_ID, where TEST_ID is a path-safe conversion from the fully qualified test descriptor, e.g. for jtreg:jdk/test:tier1 the TEST_ID is jtreg_jdk_test_tier1. This path is also printed in the log at the end of the test run.

Additional work data is stored in build/$BUILD/test-support/$TEST_ID. For some frameworks, this directory might contain information that is useful in determining the cause of a failed test.

Test suite control

It is possible to control various aspects of the test suites using make control variables.

These variables use a keyword=value approach to allow multiple values to be set. So, for instance, JTREG="JOBS=1;TIMEOUT_FACTOR=8" will set the JTReg concurrency level to 1 and the timeout factor to 8. This is equivalent to setting JTREG_JOBS=1 JTREG_TIMEOUT_FACTOR=8, but using the keyword format means that the JTREG variable is parsed and verified for correctness, so JTREG="TMIEOUT_FACTOR=8" would give an error, while JTREG_TMIEOUT_FACTOR=8 would just pass unnoticed.

To separate multiple keyword=value pairs, use ; (semicolon). Since the shell normally eats ;, the recommended usage is to write the assignment inside qoutes, e.g. JTREG="...;...". This will also make sure spaces are preserved, as in JTREG="JAVA_OPTIONS=-XshowSettings -Xlog:gc+ref=debug".

(Other ways are possible, e.g. using backslash: JTREG=JOBS=1\;TIMEOUT_FACTOR=8. Also, as a special technique, the string %20 will be replaced with space for certain options, e.g. JTREG=JAVA_OPTIONS=-XshowSettings%20-Xlog:gc+ref=debug. This can be useful if you have layers of scripts and have trouble getting proper quoting of command line arguments through.)

As far as possible, the names of the keywords have been standardized between test suites.

General keywords (TEST_OPTS)

Some keywords are valid across different test suites. If you want to run tests from multiple test suites, or just don't want to care which test suite specific control variable to use, then you can use the general TEST_OPTS control variable.

There are also some keywords that applies globally to the test runner system, not to any specific test suites. These are also available as TEST_OPTS keywords.


Currently only applies to JTReg.


Currently only applies to JTReg.


Applies to JTReg, GTest and Micro.


Applies to JTReg, GTest and Micro.


Applies to JTReg and GTest.


This keywords applies globally to the test runner system. If set to true, it enables JCov coverage reporting for all tests run. To be useful, the JDK under test must be run with a JDK built with JCov instrumentation (configure --with-jcov=<path to directory containing lib/jcov.jar>, make jcov-image).

The simplest way to run tests with JCov coverage report is to use the special target jcov-test instead of test, e.g. make jcov-test TEST=jdk_lang. This will make sure the JCov image is built, and that JCov reporting is enabled.

The JCov report is stored in build/$BUILD/test-results/jcov-output/report.

Please note that running with JCov reporting can be very memory intensive.


While collecting code coverage with JCov, it is also possible to find coverage for only recently changed code. JCOV_DIFF_CHANGESET specifies a source revision. A textual report will be generated showing coverage of the diff between the specified revision and the repository tip.

The report is stored in build/$BUILD/test-results/jcov-output/diff_coverage_report file.

JTReg keywords


The test concurrency (-concurrency).

Defaults to TEST_JOBS (if set by --with-test-jobs=), otherwise it defaults to JOBS, except for Hotspot, where the default is number of CPU cores/2, but never more than memory size in GB/2.


The timeout factor (-timeoutFactor).

Defaults to 4.


Sets the argument -timeoutHandlerTimeout for JTReg. The default value is 0. This is only valid if the failure handler is built.


The test mode (agentvm or othervm).

Defaults to agentvm.


Enable asserts (-ea -esa, or none).

Set to true or false. If true, adds -ea -esa. Defaults to true, except for hotspot.


The verbosity level (-verbose).

Defaults to fail,error,summary.


What test data to retain (-retain).

Defaults to fail,error.


Limit memory consumption (-Xmx and -vmoption:-Xmx, or none).

Limit memory consumption for JTReg test framework and VM under test. Set to 0 to disable the limits.

Defaults to 512m, except for hotspot, where it defaults to 0 (no limit).


Set the property javatest.maxOutputSize for the launcher, to change the default JTReg log limit.


JTReg keywords sent to JTReg using -k. Please be careful in making sure that spaces and special characters (like !) are properly quoted. To avoid some issues, the special value %20 can be used instead of space.


Use additional problem lists file or files, in addition to the default ProblemList.txt located at the JTReg test roots.

If multiple file names are specified, they should be separated by space (or, to help avoid quoting issues, the special value %20).

The file names should be either absolute, or relative to the JTReg test root of the tests to be run.


Use the problem lists to select tests instead of excluding them.

Set to true or false. If true, JTReg will use -match: option, otherwise -exclude: will be used. Default is false.


Additional options to the JTReg test framework.

Use JTREG="OPTIONS=--help all" to see all available JTReg options.


Additional Java options for running test classes (sent to JTReg as -javaoption).


Additional Java options to be used when compiling and running classes (sent to JTReg as -vmoption).

This option is only needed in special circumstances. To pass Java options to your test classes, use JAVA_OPTIONS.


Additional Java options that are sent to the java launcher that starts the JTReg harness.


Generate AOT modules before testing for the specified module, or set of modules. If multiple modules are specified, they should be separated by space (or, to help avoid quoting issues, the special value %20).


Retry failed tests up to a set number of times, until they pass. This allows to pass the tests with intermittent failures. Defaults to 0.


Repeat the tests up to a set number of times, stopping at first failure. This helps to reproduce intermittent test failures. Defaults to 0.


Use this report style when reporting test results (sent to JTReg as -report). Defaults to files.

Gtest keywords


The number of times to repeat the tests (--gtest_repeat).

Default is 1. Set to -1 to repeat indefinitely. This can be especially useful combined with OPTIONS=--gtest_break_on_failure to reproduce an intermittent problem.


Additional options to the Gtest test framework.

Use GTEST="OPTIONS=--help" to see all available Gtest options.


Generate AOT modules before testing for the specified module, or set of modules. If multiple modules are specified, they should be separated by space (or, to help avoid quoting issues, the special value %20).

Microbenchmark keywords


Override the number of benchmark forks to spawn. Same as specifying -f <num>.


Number of measurement iterations per fork. Same as specifying -i <num>.


Amount of time to spend in each measurement iteration, in seconds. Same as specifying -r <num>


Number of warmup iterations to run before the measurement phase in each fork. Same as specifying -wi <num>.


Amount of time to spend in each warmup iteration. Same as specifying -w <num>.


Specify to have the test run save a log of the values. Accepts the same values as -rff, i.e., text, csv, scsv, json, or latex.


Additional VM arguments to provide to forked off VMs. Same as -jvmArgs <args>


Additional arguments to send to JMH.

Notes for Specific Tests

Docker Tests

Docker tests with default parameters may fail on systems with glibc versions not compatible with the one used in the default docker image (e.g., Oracle Linux 7.6 for x86). For example, they pass on Ubuntu 16.04 but fail on Ubuntu 18.04 if run like this on x86:

$ make test TEST="jtreg:test/hotspot/jtreg/containers/docker"

To run these tests correctly, additional parameters for the correct docker image are required on Ubuntu 18.04 by using JAVA_OPTIONS.

$ make test TEST="jtreg:test/hotspot/jtreg/containers/docker" \

Non-US locale

If your locale is non-US, some tests are likely to fail. To work around this you can set the locale to US. On Unix platforms simply setting LANG="en_US" in the environment before running tests should work. On Windows or MacOS, setting JTREG="VM_OPTIONS=-Duser.language=en" helps for most, but not all test cases.

For example:

$ export LANG="en_US" && make test TEST=...
$ make test JTREG="VM_OPTIONS=-Duser.language=en" TEST=...

PKCS11 Tests

It is highly recommended to use the latest NSS version when running PKCS11 tests. Improper NSS version may lead to unexpected failures which are hard to diagnose. For example, sun/security/pkcs11/Secmod/ may fail on Ubuntu 18.04 with the default NSS version in the system. To run these tests correctly, the system property test.nss.lib.paths is required on Ubuntu 18.04 to specify the alternative NSS lib directories.

For example:

$ make test TEST="jtreg:sun/security/pkcs11/Secmod/" \

For more notes about the PKCS11 tests, please refer to test/jdk/sun/security/pkcs11/README.

Client UI Tests

Some Client UI tests use key sequences which may be reserved by the operating system. Usually that causes the test failure. So it is highly recommended to disable system key shortcuts prior testing. The steps to access and disable system key shortcuts for various platforms are provided below.


Choose Apple menu; System Preferences, click Keyboard, then click Shortcuts; select or deselect desired shortcut.

For example, test/jdk/javax/swing/TooltipManager/JMenuItemToolTipKeyBindingsTest/ fails on MacOS because it uses CTRL + F1 key sequence to show or hide tooltip message but the key combination is reserved by the operating system. To run the test correctly the default global key shortcut should be disabled using the steps described above, and then deselect "Turn keyboard access on or off" option which is responsible for CTRL + F1 combination.


Open the Activities overview and start typing Settings; Choose Settings, click Devices, then click Keyboard; set or override desired shortcut.


Type gpedit in the Search and then click Edit group policy; navigate to User Configuration -> Administrative Templates -> Windows Components -> File Explorer; in the right-side pane look for "Turn off Windows key hotkeys" and double click on it; enable or disable hotkeys.

Note: restart is required to make the settings take effect.

Editing this document

If you want to contribute changes to this document, edit doc/ and then run make update-build-docs to generate the same changes in doc/testing.html.

Override some definitions in the global css file that are not optimal for

this document.


  • '<style type="text/css">pre, code, tt { color: #1d6ae5; }</style>'