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

[Mark Sheppard]

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.

Marked as reviewed by msheppar (Reviewer).

test/jdk/javax/management/remote/mandatory/connection/DefaultAgentFilterTest.java line 174:

> 172:     private static final int FREE_PORT_ATTEMPTS = 10;
> 173: 
> 174:     private static void testDefaultAgent(String propertyFile) throws Exception {

This is a good refactoring change as it also removes some broken logic in the current retry strategy

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