RFR: JDK-8152690: main thread does not have native thread name

[Robbin Ehn]

Thanks, looks good.

/Robbin

On 03/30/2016 03:47 PM, Yasumasa Suenaga wrote:
> Hi,
>
> I uploaded new webrev.
> Could you review it?
>
>    http://cr.openjdk.java.net/~ysuenaga/JDK-8152690/webrev.01/
>
>
> Thanks,
>
> Yasumasa
>
>
> On 2016/03/30 19:10, Robbin Ehn wrote:
>> Hi,
>>
>> On 03/30/2016 11:41 AM, Yasumasa Suenaga wrote:
>>> Hi Robbin,
>>>
>>> 2016/03/30 18:22 "Robbin Ehn" <robbin.ehn at oracle.com
>>> <mailto:robbin.ehn at oracle.com>>:
>>>  >
>>>  > Hi Yasumasa,
>>>  >
>>>  >
>>>  > On 03/25/2016 12:48 AM, Yasumasa Suenaga wrote:
>>>  >>
>>>  >> Hi Robbin,
>>>  >> 2016/03/25 1:51 "Robbin Ehn" <robbin.ehn at oracle.com
>>> <mailto:robbin.ehn at oracle.com>
>>>  >> <mailto:robbin.ehn at oracle.com <mailto:robbin.ehn at oracle.com>>>:
>>>  >>
>>>  >>  >
>>>  >>  > Hi Yasumasa,
>>>  >>  >
>>>  >>  > I'm not sure why you don't set it:
>>>  >>  >
>>>  >>  > diff -r ded6ef79c770 src/share/vm/runtime/thread.cpp
>>>  >>  > --- a/src/share/vm/runtime/thread.cpp   Thu Mar 24 13:09:16 2016
>>> +0000
>>>  >>  > +++ b/src/share/vm/runtime/thread.cpp   Thu Mar 24 17:40:09 2016
>>> +0100
>>>  >>  > @@ -3584,6 +3584,7 @@
>>>  >>  >    JavaThread* main_thread = new JavaThread();
>>>  >>  >    main_thread->set_thread_state(_thread_in_vm);
>>>  >>  >    main_thread->initialize_thread_current();
>>>  >>  > +  main_thread->set_native_thread_name("main");
>>>  >>  >    // must do this before set_active_handles
>>>  >>  >    main_thread->record_stack_base_and_size();
>>>  >>  >
>>> main_thread->set_active_handles(JNIHandleBlock::allocate_block());
>>>  >>  >
>>>  >>  > here instead? Am I missing something?
>>>  >>
>>>  >> Native thread name is the same to thread name in Thread class.
>>>  >> It is set in c'tor in Thread or setName().
>>>  >> If you create new thread in Java app, native thread name will be
>>> set at
>>>  >> startup. However, main thread is already starte in VM.
>>>  >> Thread name for "main" is set in create_initial_thread().
>>>  >> I think that the place of setting thrrad name should be the same.
>>>  >
>>>  >
>>>  > Yes, I see your point. But then something like this is nicer, no?
>>>  >
>>>  > --- a/src/share/vm/runtime/thread.cpp   Tue Mar 29 09:43:05 2016
>>> +0200
>>>  > +++ b/src/share/vm/runtime/thread.cpp   Wed Mar 30 10:51:12 2016
>>> +0200
>>>  > @@ -981,6 +981,7 @@
>>>  >  // Creates the initial Thread
>>>  >  static oop create_initial_thread(Handle thread_group, JavaThread*
>>> thread,
>>>  >                                   TRAPS) {
>>>  > +  static const char* initial_thread_name = "main";
>>>  >    Klass* k =
>>> SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true,
>>> CHECK_NULL);
>>>  >    instanceKlassHandle klass (THREAD, k);
>>>  >    instanceHandle thread_oop =
>>> klass->allocate_instance_handle(CHECK_NULL);
>>>  > @@ -988,8 +989,10 @@
>>>  >    java_lang_Thread::set_thread(thread_oop(), thread);
>>>  >    java_lang_Thread::set_priority(thread_oop(), NormPriority);
>>>  >    thread->set_threadObj(thread_oop());
>>>  > -
>>>  > -  Handle string = java_lang_String::create_from_str("main",
>>> CHECK_NULL);
>>>  > +
>>>  > +  thread->set_native_thread_name(initial_thread_name);
>>>  > +
>>>  > +  Handle string =
>>> java_lang_String::create_from_str(initial_thread_name, CHECK_NULL);
>>>  >
>>>  >    JavaValue result(T_VOID);
>>>  >    JavaCalls::call_special(&result, thread_oop,
>>>
>>> Okay, I will upload new webrev later.
>>
>> Thanks!
>>
>>>
>>>  >>  > The launcher seem to name itself 'java' and naming this thread
>>> just
>>>  >>  > 'main' is confusing to me.
>>>  >>  >
>>>  >>  > E.g. so main thread of the process (and thus the process) is
>>> 'java' but
>>>  >>  > first JavaThread is 'main'.
>>>  >>
>>>  >> The native main thread in the process is not JavaThread. It is
>>> waiting
>>>  >> for ending of Java main thread with pthread_join().
>>>  >> set_native_thread_name() is for JavaThread. So I think that we do
>>> not
>>>  >> need to call it for native main thread.
>>>  >
>>>  >
>>>  > Not sure if we can change it anyhow, since we want java and native
>>> name to be the same and java thread name might have some dependents.
>>>  >
>>>  > The name is visible in e.g. /proc.
>>>  >
>>>  > $ ps H -C java -o 'pid tid comm' | head -4
>>>  >   PID   TID COMMAND
>>>  >  6423  6423 java
>>>  >  6423  6424 main
>>>  >  6423  6425 GC Thread#0
>>>  >
>>>  > It would be nice with something like 'Java Main Thread'.
>>>
>>> I do not think so.
>>> Native main thread might not be a Java launcher - e.g. Apache
>>> commons-daemon, JNI application, etc.
>>>
>>> If you want to change native main thread name, I think that we have to
>>> change Java launcher code.
>>> Should I include it in new webrev?
>>
>> No
>>
>> Thanks again!
>>
>> /Robbin
>>
>>>
>>> Thanks,
>>>
>>> Yasumasa
>>>
>>>  > Thanks
>>>  >
>>>  > /Robbin
>>>  >
>>>  >
>>>  >>
>>>  >> Thanks,
>>>  >>
>>>  >> Yasumasa
>>>  >>
>>>  >>  > Thanks!
>>>  >>  >
>>>  >>  > /Robbin
>>>  >>  >
>>>  >>  > On 03/24/2016 03:26 PM, Yasumasa Suenaga wrote:
>>>  >>  > > Hi all,
>>>  >>  > >
>>>  >>  > > HotSpot for Linux will set thread name via
>>> pthread_setname_np().
>>>  >>  > > However, main thread does not have it.
>>>  >>  > >
>>>  >>  > > All JavaThread have native name, and main thread is JavaThread.
>>>  >>  > > For consistency, main thread should have native thread name.
>>>  >>  > >
>>>  >>  > > I uploaded a webrev. Could you review it?
>>>  >>  > >
>>>  >>  > > http://cr.openjdk.java.net/~ysuenaga/JDK-8152690/webrev.00/
>>>  >>  > >
>>>  >>  > > I cannot access JPRT.
>>>  >>  > > So I need a sponsor.
>>>  >>  > >
>>>  >>  > >
>>>  >>  > > Thanks,
>>>  >>  > >
>>>  >>  > > Yasumasa
>>>  >>  > >
>>>  >>
>>>