RFR: JDK-8196356: Changes to m4 files don't trigger autoconf execution at build time

[Magnus Ihse Bursie]

On 2018-02-10 23:39, Martin Buchholz wrote:
> I agree.  Once you make something lazy-initted you have a concurrency
> problem.  And there's no CAS or lock on the filesystem.  What happens if
> two configure processes run at exactly the same time, perhaps even with
> different versions of autoconf?  If you lazy-generate configure, it must be
> written outside the source tree.
That is of course a problem with the entire build system, and is 
certainly not unique to this problem. What happens if you run "make" 
concurrently in the same directory? Catastrophe! Or if you run 
"configure" at the same time? Disaster! Creating the file outside the 
source tree will not help in the slightest regard; you can just as well 
create a race condition in any place you select. This does not sound 
like a real-world problem that one has to safe-guard against.

/Magnus

>
> On Sat, Feb 10, 2018 at 3:29 AM, Thomas Stüfe <thomas.stuefe at gmail.com>
> wrote:
>
>> On Sat, Feb 10, 2018 at 9:12 AM, Alan Bateman <Alan.Bateman at oracle.com>
>> wrote:
>>
>>> On 08/02/2018 17:49, Erik Joelsson wrote:
>>>
>>>> The check for when to generate the generated configure script is not
>>>> working quite as expected. It currently only compares timestamps if the
>>>> local repository has any local changes in the make/autoconf directory.
>> This
>>>> used to make sense when we had a committed generated script, but now we
>>>> actually do need to regenerate any time an input file is newer than the
>>>> generated script.
>>>>
>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8196356
>>>>
>>> In addition to `hg status` showing no changes, I think it will continue
>> to
>>> confuse people to generate it into a hidden directory. Was there any
>>> consideration to generating into a regular directory?
>>>
>>>
>> I agree. Also, we still generate the configure.sh into the source tree even
>> if the output directory is somewhere else. I always keep my output
>> directories separate from the source tree. Sometimes my source directory is
>> even on a read-only share. I would prefer and also expect any temporary
>> files to be placed in the output directory resp. the current directory, not
>> in the source tree. Would that be possible?
>>
>> Thanks and Kind Regards, Thomas
>>
>>
>>> -Alan
>>>