RFR: JDK-8154331: main thread should be treated as JNI-attached thread.

[Yasumasa Suenaga]

Hi David,

> Correcting this behaviour could be seen as
> a regression because there would no be no way to set the native name of
> the main thread.

If my proposal in JDK-8152690 [1] is merged, Java developer can change native
thread name with reflection.

IMHO, we can merge changes for jvm.cpp and Thread.{c,java} to this issue
from JDK-8152690.

Thanks,

Yasumasa


[1] http://mail.openjdk.java.net/pipermail/core-libs-dev/2016-April/040276.html


On 2016/04/16 16:25, David Holmes wrote:
> Hi Yasumasa,
> 
> On 15/04/2016 11:23 PM, Yasumasa Suenaga wrote:
>> Hi all,
>>
>> In discussion about JDK-8152690 [1], we were found a bug.
>> Java main thread which is started by Java launcher is not treated as JNI-attached thread.
>>
>> I uploaded a webrev.
>> Could you review it?
>>
>>     http://cr.openjdk.java.net/~ysuenaga/JDK-8154331/webrev.00/
>>
>> I cannot access JPRT.
>> So I need a sponsor.
> 
> As I just wrote in the bug report:
> 
> I think it was an oversight that when the OSX port brought this code in,
> the main thread was not marked as being a JNI-attached thread - as
> suggested by this comment:
> 
> JavaThread(bool is_attaching_via_jni = false); // for main thread and
> JNI attached threads
> 
> However because of this oversight a call to Thread.setName from the main
> thread would** cause the native thread name to be set (normally we don't
> modify JNI-attached threads). Correcting this behaviour could be seen as
> a regression because there would no be no way to set the native name of
> the main thread.
> 
> Given that we don't actually gain anything by "fixing" this I'm inclined
> to simply leave it as-is.
> 
> ** I haven't actually verified this as I don't have access to a system I
> can check it on right now. But based on code inspection this appears to
> be the case.
> 
> Thanks,
> David
> 
>>
>> Thanks,
>>
>> Yasumasa
>>
>>
>> [1] http://mail.openjdk.java.net/pipermail/core-libs-dev/2016-April/040251.html
>>