Fwd: Re: RFR: 8079408: Reimplement TraceClassLoading, TraceClassUnloading, and TraceClassLoaderData with Unified Logging.

Max Ockner max.ockner at oracle.com
Thu Jan 28 19:29:02 UTC 2016

Forwarded private discussion with Ioi about changing the test to use 

Hopefully nearing the end:

Webrev: http://cr.openjdk.java.net/~mockner/classload.08/

-------- Original Message --------
Subject: 	Re: RFR: 8079408: Reimplement TraceClassLoading, 
TraceClassUnloading, and TraceClassLoaderData with Unified Logging.
Date: 	Thu, 28 Jan 2016 10:57:15 -0800
From: 	Ioi Lam <ioi.lam at oracle.com>
To: 	Max Ockner <max.ockner at oracle.com>

Hi Max,

Thanks for doing this. Also, I sent the e-mail to you personally, so you 
may want to post the new version in the open list for record purpose.

- Ioi

On 1/28/16 8:11 AM, Max Ockner wrote:
> Ioi,
> I have replaced my test with this test that you have given me (thank 
> you!)
> I also have removed the commented out section which used to test for 
> "making nmethod ...", and I have added the comment that you suggested 
> at the top of ClassUnloadCommon.java
> Thanks,
> Max
> On 1/27/2016 7:13 PM, Ioi Lam wrote:
>> On 1/27/16 12:51 PM, Max Ockner wrote:
>>> Though Ioi suggested I change my new test, I have not done that. I 
>>> was recommended to copy from runtime/ClassUnload/UnloadTest.java 
>>> instead of rolling my own test for class unloading. I mentioned that 
>>> it was tricky to make the new test work, but it was tricky because I 
>>> was trying to copy from UnloadTest.java. This test refers to a class 
>>> "test.Empty" from a "classes" library, but the new test has a 
>>> processBuilder which I think does not play nicely with the class 
>>> path for  "test.Empty". In the end it was much easier to hardcode 
>>> the entire test into one place than to follow UnloadTest.java and 
>>> refer to extra libraries.
>> Hi Max,
>> I've written a version of ClassLoadUnloadTest.java using 
>> ClassUnloadCommon. The main trick is here:
>>         Collections.addAll(argsList, "-Dtest.classes=" + 
>> System.getProperty("test.classes","."));
>> That's because of this line in ClassUnloadCommon:
>>             return new URLClassLoader(new URL[] {
>> Paths.get(System.getProperty("test.classes",".") + File.separatorChar 
>> + "classes").toUri().toURL(),
>>             }, null);
>> When Jtreg launches a sub-process, it strips off all the Java system 
>> properties, so you need to add the "-D" in the command-line.
>> I also disabled the test related to "making nmethod ... unloadable". 
>> As Rachel found out in JDK-8146137, the compiler is unpredictable. 
>> Even if you invoke a method 10001 times, there's no guaranteed that 
>> it will always be compiled. Since this is not an 'easy-to-test' 
>> feature, we should just skip it.
>> I would also suggest adding this to the header of ClassUnloadCommon.java
>> /*
>>  * To use ClassUnloadCommon from a sub-process, see 
>> hotspot/test/runtime/logging/ClassLoadUnloadTest.java
>>  * for an example.
>>  */
>> What do you think?
>> - Ioi

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