Hi Daniil,

On 14/03/2018 3:26 PM, Daniil Titov wrote:
Please review the changes that fix intermittent timeout failure of 
serviceability/dcmd/framework/* tests.

The problem here is that these tests invoke jcmd in different ways and one of 
such ways is when a main class is passed to the jcmd as a VM identifier. The 
main class for jtreg test is com.sun.javatest.regtest.agent.MainWrapper and in 
some cases more than one test are running in parallel and there are multiple 
Java processes with com.sun.javatest.regtest.agent.MainWrapper as a main class 
. When it happens jcmd iterates over all Java processes that match the 
condition (the main class equals to com.sun.javatest.regtest.agent.MainWrapper) 
and executes the command for each of them. That results in the jcmd invokes the 
given command multiple times and attaches to Java processes not related to the 
current test.

It's good to finally find the root cause of the problem!

The fix makes serviceability/dcmd/framework/* tests non-concurrent to ensure 
that they don't interact with other tests.

This seems more of a workaround than a fix - though I don't know whether there is a way to distinguish multiple VMs all running what appears to be the same main class.

My concern with the fix is how long it will take to run these tests sequentially, as they are run in tier2 and as part of the CI test job?


Bug: https://bugs.openjdk.java.net/browse/JDK-8166642
Webrev: http://cr.openjdk.java.net/~dtitov/8166642/webrev.01

The tests ran successfully with Mach5.

Best regards,

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