Dale, Thanks for doing this work and especially for adding these guidelines
to the Wiki!
On Thu, Nov 4, 2021 at 1:08 PM Dale Emery wrote:
> As of July, 2021, Geode's build system no longer executes test worker
> processes in separate Docker containers.
>
> This increases the risk of port collisions between tests. Each test worker
> JVM and each Java process started by a test executes directly in the
> environment provided by the host machine. If a test is using a port, any
> concurrently running test that tries to bind to the same port number will
> suffer a BindException.
> Safely allocating ports. To reduce this risk, Geode's build system now
> assigns each test worker JVM a distinct range of ports. In CI, which runs
> 24 distributed tests concurrently, each test gets a range of about 400
> ports.
> In JVMs running Geode version 1.14 or later, AvailablePort and
> AvailablePortHelper will choose ports from this assigned range. As a
> result, no two tests will ever receive the same port number from these
> classes, no matter how many are running concurrently.
> When you write a test, keep the following guidelines in mind, to make sure
> your test uses only the ranges of ports that the Geode build system
> assigned to it:
>
> * To assign an available port, call AvailablePortHelper or
> AvailablePort. These are the only classes that know about the reduced port
> range for the test.
> * Call AvailablePort and AvailablePortHelper only in the current
> version of Geode. Do not call these classes in Child VMs running older
> versions of Geode. Older versions of Geode do not honor the new, reduced
> port ranges.
> * Do not launch any service using Geode’s default port for that
> service. Always explicitly assign an available port. The only safe use of
> default ports is in a test to verify that a service uses its default port
> by default. Note that such a test will fail the stress test CI job. To
> exclude such a test from the stress test job, annotate it with
> @Category(IgnoreInRepeatTestTasks.class).
> * Do not launch any service using a port number hard-coded into the
> test. Always explicitly assign an available port. There is no safe use of
> any hard-coded port number in tests that can run concurrently.
> * Do not attempt to reuse an ephemeral port. Some tests start a member
> on an ephemeral port, stop the member, and attempt to restart it on the
> same port. This is not safe. It was never safe. During the time between
> when the member stops and when it restarts, the port is available for the
> operating system to give to any other process. In CI, it is very, very
> likely that one or more concurrently-running tests (or other processes)
> will request ephemeral ports during the time when your test is not bound to
> it. If one of those processes gets the port your test was using, your test
> will fail.
> This information is available on the Geode wiki:
> https://cwiki.apache.org/confluence/display/GEODE/Using+Ports+Safely+in+Tests
>
> Dale
>
>
