Why is fork1() exported from hotspot?

[Thomas Stüfe]

Hi,

thanks for looking this up!

I think the code just shuffled around the pre-existing fork1() definition
and added an JNIEXPORT.

But in the older version, there is a comment about green threads in the JDK:

-/**
- * NOTE: the following code is to keep the green threads code
- * in the libjava.so happy. Once the green threads is removed,
- * these code will no longer be needed.
- */
-....
-int
-fork1() {
-    return fork();
-}
-

I do not think JDK uses green threads anymore.

Kind Regards, Thomas


On Wed, Oct 21, 2015 at 10:57 AM, Lindenmaier, Goetz <
goetz.lindenmaier at sap.com> wrote:

> Hi,
>
> the comment was added in 2011 by
> "6588413: Use -fvisibility=hidden for gcc compiles"
> http://hg.openjdk.java.net/jdk9/hs-rt/hotspot/rev/d70fe6ab4436
> while the export & function already existed.
>
> Unfortunately, this change doesn't unveil who is using the symbol.
>
> Best regards,
>   Goetz.
>
> > -----Original Message-----
> > From: hotspot-runtime-dev [mailto:hotspot-runtime-dev-
> > bounces at openjdk.java.net] On Behalf Of Christian Thalinger
> > Sent: Mittwoch, 21. Oktober 2015 01:56
> > To: Thomas Stüfe
> > Cc: hotspot-runtime-dev at openjdk.java.net
> > Subject: Re: Why is fork1() exported from hotspot?
> >
> >
> > > On Oct 19, 2015, at 9:14 PM, Thomas Stüfe <thomas.stuefe at gmail.com>
> > wrote:
> > >
> > > Hi all,
> > >
> > > on Linux we define and export "fork1()" - a stub for fork() - and
> "fork1"
> > > also appears in linker mapfiles for bsd and AIX. The latter, I am
> sure, is
> > > just a copy-paste-effect.
> > >
> > > Why do we need to define and export fork1() for non-solaris platforms?
> > We
> > > only ever use it on Solaris.
> > >
> > > The comment in os_linux.cpp is not really enlightening:
> > > "// Something to do with the numa-aware allocator needs these symbols”
> >
> > Can you see what changeset added this comment or was it before Mercurial?
> >
> > >
> > > Does anyone know why this is needed?
> > >
> > > Regards, Thomas
>
>