RFR : 8195857 : Posix platforms : move os::is_headless_jre check coding to os::Posix and remove test for libmawt
David Holmes
david.holmes at oracle.com
Thu Jan 25 12:16:03 UTC 2018
On 25/01/2018 10:08 PM, Baesken, Matthias wrote:
>
>>> Would it make sense to rename the bug to "Remove os::is_headless_jre"?
>>
>> +1 on that too!
>>
>
> Hi David and Goetz, I renamed the bug .
>
> So we have 2 reviews now --> who can push it for me ?
I can sponsor it for you, but I'll let it sit for a while to give a
chance for any other comments.
Thanks,
David
> Best regards, Matthias
>
>
>> -----Original Message-----
>> From: David Holmes [mailto:david.holmes at oracle.com]
>> Sent: Donnerstag, 25. Januar 2018 12:57
>> To: Baesken, Matthias <matthias.baesken at sap.com>; Bob Vandette
>> <bob.vandette at oracle.com>
>> Cc: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>; hotspot-
>> dev at openjdk.java.net
>> Subject: Re: RFR : 8195857 : Posix platforms : move os::is_headless_jre check
>> coding to os::Posix and remove test for libmawt
>>
>> On 25/01/2018 7:15 PM, Lindenmaier, Goetz wrote:
>>> Hi,
>>>
>>> Change looks good :)
>>
>> +1 - thanks Matthias!
>>
>>> Would it make sense to rename the bug to "Remove os::is_headless_jre"?
>>
>> +1 on that too!
>>
>> David
>> ------
>>
>>> Best regards,
>>> Goetz.
>>>
>>> -----Original Message-----
>>> From: Baesken, Matthias
>>> Sent: Thursday, January 25, 2018 8:49 AM
>>> To: David Holmes <david.holmes at oracle.com>; Bob Vandette
>> <bob.vandette at oracle.com>
>>> Cc: hotspot-dev at openjdk.java.net; Lindenmaier, Goetz
>> <goetz.lindenmaier at sap.com>
>>> Subject: RE: RFR : 8195857 : Posix platforms : move os::is_headless_jre
>> check coding to os::Posix and remove test for libmawt
>>>
>>> Hi David, I created a new webrev :
>>>
>>> http://cr.openjdk.java.net/~mbaesken/webrevs/8195857.1/
>>>
>>> This one removes os::is_headless_jre() .
>>>
>>> Please review.
>>>
>>> Thanks, Matthias
>>>
>>>
>>>> -----Original Message-----
>>>> From: David Holmes [mailto:david.holmes at oracle.com]
>>>> Sent: Donnerstag, 25. Januar 2018 07:39
>>>> To: Baesken, Matthias <matthias.baesken at sap.com>; Bob Vandette
>>>> <bob.vandette at oracle.com>
>>>> Cc: hotspot-dev at openjdk.java.net
>>>> Subject: Re: RFR : 8195857 : Posix platforms : move os::is_headless_jre
>> check
>>>> coding to os::Posix and remove test for libmawt
>>>>
>>>> Hi Matthias,
>>>>
>>>> On 25/01/2018 4:36 PM, Baesken, Matthias wrote:
>>>>>>
>>>>>> Bottom line: os::is_headless_jre() is dead code as far as I can see.
>>>>>>
>>>>>
>>>>> Hi David, so do you suggest I prepare a new webrev where
>>>> os::is_headless_jre() is completely removed ?
>>>>>
>>>>> What about the code block in hotspot/share/runtime/arguments.cpp ,
>> do
>>>> you think this can be completely removed as well ?
>>>>
>>>> Yes - everything pertaining to os::is_headless_jre() can be removed.
>>>>
>>>> Thanks,
>>>> David
>>>> -----
>>>>
>>>>>
>>>>> 3495 if (os::is_headless_jre()) {
>>>>> 3496 const char* headless =
>>>> Arguments::get_property("java.awt.headless");
>>>>> 3497 if (headless == NULL) {
>>>>> 3498 const char *headless_env = ::getenv("JAVA_AWT_HEADLESS");
>>>>> 3499 if (headless_env == NULL) {
>>>>> 3500 if (!add_property("java.awt.headless=true")) {
>>>>> 3501 return JNI_ENOMEM;
>>>>> 3502 }
>>>>> 3503 } else {
>>>>> 3504 char buffer[256];
>>>>> 3505 jio_snprintf(buffer, sizeof(buffer), "java.awt.headless=%s",
>>>> headless_env);
>>>>> 3506 if (!add_property(buffer)) {
>>>>> 3507 return JNI_ENOMEM;
>>>>> 3508 }
>>>>> 3509 }
>>>>> 3510 }
>>>>> 3511 }
>>>>>
>>>>> Best regards, Matthias
>>>>>
>>>>>
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: David Holmes [mailto:david.holmes at oracle.com]
>>>>>> Sent: Donnerstag, 25. Januar 2018 02:16
>>>>>> To: Bob Vandette <bob.vandette at oracle.com>
>>>>>> Cc: Baesken, Matthias <matthias.baesken at sap.com>; hotspot-
>>>>>> dev at openjdk.java.net
>>>>>> Subject: Re: RFR : 8195857 : Posix platforms : move os::is_headless_jre
>>>> check
>>>>>> coding to os::Posix and remove test for libmawt
>>>>>>
>>>>>> On 24/01/2018 11:16 PM, Bob Vandette wrote:
>>>>>>>> On Jan 23, 2018, at 5:50 PM, David Holmes
>> <david.holmes at oracle.com>
>>>>>> wrote:
>>>>>>>>
>>>>>>>> Hi Bob,
>>>>>>>>
>>>>>>>> On 24/01/2018 1:25 AM, Bob Vandette wrote:
>>>>>>>>> If we are going to preserve this functionality and make alterations, I
>>>>>> suggest that
>>>>>>>>> we try to move this into the desktop module and remove it from
>> the
>>>>>> hotspot sources.
>>>>>>>>> Other than finding an appropriate path at startup to initialize the
>>>>>> property, there is
>>>>>>>>> no reason why this check can’t be written in Java. This
>> functionality
>>>> has
>>>>>> nothing to
>>>>>>>>> do with Hotspot or VMs. (I should have probably done this when I
>>>> first
>>>>>> added this check).
>>>>>>>>
>>>>>>>> Well we hacked it into the SE Embedded builds so we knew what lib
>>>> was
>>>>>> missing.
>>>>>>>>
>>>>>>>> I don't think what you suggest really makes sense in a modular world
>>>>>> because I don't think we expect to have java.desktop but not some of
>> its
>>>>>> native parts - so there would be no trigger to force into headless mode.
>>>>>> More likely there is simply no java.desktop module at all.
>>>>>>> The automatic setting of java.awt.headless has nothing to do with
>>>> compact
>>>>>> profiles. This support was available in JDK 7 before profiles even
>> existed.
>>>>>> This
>>>>>>> automatic headless detection was added in order to allow Java to be
>>>>>> ported to platforms that do not have a native windowing toolkit
>> available.
>>>>>> This was
>>>>>>> used in embedded to also reduce the size of the binary by removing
>> this
>>>>>> big library. A configuration that contains java.desktop can absolutely be
>>>>>> supported
>>>>>>> and the JCK can be passed without this native library.
>>>>>>>
>>>>>>> This Java property is only referenced by the desktop module. This is
>> why
>>>> I
>>>>>> suggested that this functionality be moved out of the hotspot VM.
>>>>>>
>>>>>> Yes we forced the AWT into headless mode if there was no native
>>>> graphics
>>>>>> library support available. For some of those platforms we even did this
>>>>>> at build time, not via a runtime check. For SE Embedded support we
>>>> would
>>>>>> strip the library out at image build time, and so the runtime check
>>>>>> would force AWT into headless mode. For compact profiles there is no
>>>> AWT
>>>>>> at all, and no native library in the built image so the runtime check
>>>>>> still (vacuously) sets the property for headless mode.
>>>>>>
>>>>>> If you have the java.desktop module, then you have everything - there
>> is
>>>>>> no fragmentation of that module that I am aware of, that would allow
>> you
>>>>>> strip out the library that triggers os::is_headless_jre() or some other
>>>>>> check that forces the AWT into headless mode. If you have
>> java.desktop
>>>>>> and you want headless mode then you have to ask for it explicitly.
>>>>>>
>>>>>> Bottom line: os::is_headless_jre() is dead code as far as I can see.
>>>>>>
>>>>>> Separately I'll file a bug to remove the compact profile builds.
>>>>>>
>>>>>> David
>>>>>> -----
>>>>>>
>>>>>>> Bob.
>>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>> That said I was reminded that this is also used by the Compact
>> Profiles
>>>>>> that were added in Java 8, but for which support was removed as from
>>>> Java 9
>>>>>> (and modules). However the build logic is still present, and they still use
>>>> this
>>>>>> functionality. I think we can remove compact profiles completely in JDK
>>>> 11,
>>>>>> but that's a seperate tasks.
>>>>>>>>
>>>>>>>> Meanwhile if we kill off the os::is_headless_jre() logic then the
>>>> compact
>>>>>> profiles would not default to headless mode even though they can't
>> run
>>>>>> headful (due to the missing native library as well as other Java APIs).
>> But
>>>> the
>>>>>> only impact I can see there would be for running tests - and we're not
>>>> testing
>>>>>> compact profiles. So ... I still think this can be removed, but want to do
>> a
>>>>>> couple more checks.
>>>>>>>>
>>>>>>>> Cheers,
>>>>>>>> David
>>>>>>>>
>>>>>>>>> Bob.
>>>>>>>>>> On Jan 23, 2018, at 5:57 AM, Baesken, Matthias
>>>>>> <matthias.baesken at sap.com> wrote:
>>>>>>>>>>
>>>>>>>>>> Hi David, thanks for the comments.
>>>>>>>>>>
>>>>>>>>>>> I'd need to do some checking but I think this may all be
>> effectively
>>>>>>>>>>> dead code.
>>>>>>>>>>
>>>>>>>>>> Please do the checking, maybe we can completely remove it.
>>>>>>>>>>
>>>>>>>>>> Best Regards, Matthias
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>> -----Original Message-----
>>>>>>>>>>> From: David Holmes [mailto:david.holmes at oracle.com]
>>>>>>>>>>> Sent: Dienstag, 23. Januar 2018 11:30
>>>>>>>>>>> To: Baesken, Matthias <matthias.baesken at sap.com>; 'hotspot-
>>>>>>>>>>> dev at openjdk.java.net' <hotspot-dev at openjdk.java.net>
>>>>>>>>>>> Subject: Re: RFR : 8195857 : Posix platforms : move
>>>>>> os::is_headless_jre check
>>>>>>>>>>> coding to os::Posix and remove test for libmawt
>>>>>>>>>>>
>>>>>>>>>>> Hi Matthias,
>>>>>>>>>>>
>>>>>>>>>>> Some preliminary comments ...
>>>>>>>>>>>
>>>>>>>>>>> On 23/01/2018 6:24 PM, Baesken, Matthias wrote:
>>>>>>>>>>>> Hello, I noticed that os::is_headless_jre() still checks on the
>>>> Posix
>>>>>>>>>>> platforms for libmawt which is not present any longer.
>>>>>>>>>>>
>>>>>>>>>>> I wonder why that comment was put in but the code not
>> changed
>>>> ...
>>>>>>>>>>>
>>>>>>>>>>>> Additionally the os::is_headless_jre() function could be put in
>> a
>>>>>> central
>>>>>>>>>>> place at os_posix to avoid code duplication.
>>>>>>>>>>>
>>>>>>>>>>> I think you could simplify further and just define in os.cpp with
>>>> three
>>>>>>>>>>> cases: windows, OS X, posix. I normally wouldn't suggest that but
>>>>>> given
>>>>>>>>>>> Windows and OS X are always false, it's quite trivial.
>>>>>>>>>>>
>>>>>>>>>>> That said this may simplify even further because I don't know if
>> the
>>>>>>>>>>> concept of a headless JRE is even meaningful anymore. This
>> what
>>>> put
>>>>>> in
>>>>>>>>>>> place in 2010 to support Java SE Embedded. We had a special
>> build
>>>>>>>>>>> process that would remove the library from the JRE image, then
>> a
>>>>>> runtime
>>>>>>>>>>> check os::is_headless_jre() run during argument processing, that
>> if
>>>>>>>>>>> true, caused the java.awt.headless property to be set to true
>>>> (unless
>>>>>>>>>>> already set). I don't think we can even build a "headless JRE" any
>>>>>> more.
>>>>>>>>>>>
>>>>>>>>>>> I'd need to do some checking but I think this may all be
>> effectively
>>>>>>>>>>> dead code.
>>>>>>>>>>>
>>>>>>>>>>> Thanks,
>>>>>>>>>>> David
>>>>>>>>>>> -------
>>>>>>>>>>>
>>>>>>>>>>>> Could you please review my change .
>>>>>>>>>>>>
>>>>>>>>>>>> Webrev :
>>>>>>>>>>>>
>>>>>>>>>>>> http://cr.openjdk.java.net/~mbaesken/webrevs/8195857/
>>>>>>>>>>>>
>>>>>>>>>>>> Bug :
>>>>>>>>>>>>
>>>>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8195857
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Thanks, Matthias
>>>>>>>>>>>>
>>>>>>>
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