jmx-dev RFR: 8206187: javax/management/remote/mandatory/connection/DefaultAgentFilterTest.java fails with Port already in use [v2]

[Kevin Walls]

On Thu, 24 Feb 2022 12:17:54 GMT, Kevin Walls <kevinw at openjdk.org> wrote:

>> Test fails occasionally due to a port clash.
>> Presumably the port that was returned by Utils.getFreePort(), is no longer free.
>> The test creates a ProcessBuilder with the parameters for JMX, including port number, and uses that to create a new Process.
>> It should retry with a new port if we fail due to a port in use, for some limited number of attempts.
>> 
>> main already has some retry logic, but not working:
>> it checks for an InvocationTargetException to contain a BindException, but it simply gets a BindException, thrown by TestAppRun.start().
>> TestAppRun.start() runs the new process and scans for errors, but on failure its predicate has only seen the first line of a failure, so a BindException is never recognised and thrown.
>> Also main does not limit the retries, and handling the port retry in main() is duplicated, for each run of the test method.
>> 
>> So...
>> 
>> Make the error-scanning predicate in TestAppRun recognise a "port in use" message and throw a BindExeption.  This is a notification to the caller that it failed, it's not the actual BindException as that was thrown in a different process.
>> Make the testDefaultAgent method (the main part of the test) handle retrying with a new port, a limited number of times.
>
> Kevin Walls has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Clarify predicate usage.

Thanks for the reviews!

Apologies, one more update - I had a break in there earlier to terminate the retry loop, and I removed it accidentally when changing things to make it fail.
The retry loop has to let the testDefaultAgent method complete normally (which needs the break), or by throwing an Exception.
Both looking good now.

-------------

PR: https://git.openjdk.java.net/jdk/pull/7589