RFR(s): 8212828: (process) Change the Process launch mechanism default on Linux to be posix_spawn
Roger Riggs
roger.riggs at oracle.com
Wed Feb 13 15:56:28 UTC 2019
Hi Thomas,
This is a change that should have a release note, can you fill it in:
https://bugs.openjdk.java.net/browse/JDK-8218924
Also, I had to do some manual updates to the issues to get the changeset
into the history.
The issue number should have been 8213192 in the summary lineand on the
emails.
Hgupdater watches the commits and uses the bugid to update the bug;
wrong bug, wrong updates.
Thanks, Roger
On 2/12/19 1:41 AM, Thomas Stüfe wrote:
>
>
> On Mon, Feb 11, 2019 at 9:18 PM Martin Buchholz <martinrb at google.com
> <mailto:martinrb at google.com>> wrote:
>
> Looks good to me.
>
>
> Thank you, I just pushed.
>
> It's true that these tests depending on external tools are very
> brittle.
> In particular, strace is in the middle of a flag re-org
>
> -e trace=%process
> -e trace=process (deprecated)
>
> Nevertheless, we have such tests - are they worth the maintenance
> burden?
> My own Zombies.java test is a good example.
>
>
> It is more useful than my proposed test was. I wince a bit at the perl
> requirement though. Especially since the test silently quits if no
> perl is installed.
>
> (As a side note, I wonder whether we could have a mechanism to signal
> requirements not met, eg. with a TestRequirementsNotMetException, and
> then let the test executor decide what to do: warn, ignore, error...)
>
> I guess part of this could be redone nowadays with Rogers
> ProcessHandle API (the child seeking), but we still would need to find
> out if the child is a zombie.
>
> I like the test name btw. Very succinct :)
>
> ..Thomas
>
>
>
>
> On Mon, Feb 11, 2019 at 10:50 AM Thomas Stüfe
> <thomas.stuefe at gmail.com <mailto:thomas.stuefe at gmail.com>> wrote:
>
> Hi Roger, Martin,
>
> hopefully final version:
>
> http://cr.openjdk.java.net/~stuefe/webrevs/8213192--(process)-change-the-process-launch-mechanism-default-on-linux-to-be-posix_spawn/webrev.03/webrev/
>
> I removed the test and the changes in the test library made
> for the test. Test is just too brittle with too little
> nourishing value. Everything else is unchanged from webrev.02.
>
> Thank you, Thomas
>
>
>
> On Fri, Feb 8, 2019 at 10:38 AM Thomas Stüfe
> <thomas.stuefe at gmail.com <mailto:thomas.stuefe at gmail.com>> wrote:
>
> Hi Roger, Martin,
>
> next version:
>
> http://cr.openjdk.java.net/~stuefe/webrevs/8213192--(process)-change-the-process-launch-mechanism-default-on-linux-to-be-posix_spawn/webrev.02/webrev
>
> - did massage the comment in ProcessImpl.c
> - made the test more resilient by scanning for the strace
> tool and by silently ignoring all problems stemming from
> strace or the payload binary not being there. The test now
> only fails if the forks were successully executed but it
> does not seem to use posix-spawn.
> - added output to the test by printing the "interesting"
> lines of the strace output. Note that this filtering is
> not really sophisticated and will show all thread related
> clone() calls as well:
>
> 614 [pid 12447] <... clone resumed>
> child_stack=0x7fe00c4baff0,
> flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID,
> parent_tidptr=0x7fe00c4bb9d0, tls=0x7fe00c4bb700,
> child_tidptr=0x7fe00c4bb9d0) = 12452
> 646 [pid 12447] clone(/usr/bin/strace: Process 12453
> attached
> 649 [pid 12447] <... clone resumed>
> child_stack=0x7fe00c3b9ff0,
> flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID,
> parent_tidptr=0x7fe00c3ba9d0, tls=0x7fe00c3ba700,
> child_tidptr=0x7fe00c3ba9d0) = 12453
> ....
>
> I am sure this could be made more intelligent but lets
> keep it simple for now.
>
> - I removed the helperPath() methods Roger mentioned, they
> are not needed anymore.
>
> @Martin: I like the -e signal=none -e trace=process idea
> but I'm not sure if all versions of strace support these
> options. I think the strace output is small enough for
> this small use case, some kB only.
>
> Cheers, Thomas
>
>
>
>
>
> On Thu, Feb 7, 2019 at 6:01 PM Thomas Stüfe
> <thomas.stuefe at gmail.com <mailto:thomas.stuefe at gmail.com>>
> wrote:
>
> Hi all,
>
> second version, including the updated comment in
> ProcessImpl.c Martin requested:
>
> http://cr.openjdk.java.net/~stuefe/webrevs/8213192--(process)-change-the-process-launch-mechanism-default-on-linux-to-be-posix_spawn/webrev.01/webrev/index.html
>
> @Roger: thanks for feeding this into your tests. I
> still try to get it to run thru jdk-submit, but that
> seems to be stuck again..
>
> Cheers, Thomas
>
>
>
>
>
> On Wed, Feb 6, 2019 at 10:29 AM Thomas Stüfe
> <thomas.stuefe at gmail.com
> <mailto:thomas.stuefe at gmail.com>> wrote:
>
> Hi all
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8213192
> webrev:
> http://cr.openjdk.java.net/~stuefe/webrevs/8213192--(process)-change-the-process-launch-mechanism-default-on-linux-to-be-posix_spawn/webrev.00/webrev/index.html
>
> (@Roger: I hope you do not mind? The bug is
> assigned to you but since I happened to play
> around with posix_spawn I prepared this webrev. If
> you rather do this change, that is fine and I will
> leave it to you.)
>
> When we added the possibility to use posix_spawn
> as underlying implementation for Runtime.exec() on
> Linux with
> https://bugs.openjdk.java.net/browse/JDK-8212828,
> we agreed to keep VFORK as default until work on
> 13 starts. So now would be a good time to switch
> the default to posix_spawn to get a good testing
> window. Note that at SAP we run our VMs internally
> with posix_spawn as default since some months and
> have not seen problems.
>
> As for the fix, I added a test which tests that
> the default is indeed posix_spawn - not sure
> whether this is overdoing it though. Also, I use
> strace for the test, and /bin/true, and while
> strace is usually available and reachable by path
> resolution, I am afraid on some test machines it
> may not. What do you think, should I leave the
> test out?
>
> The fix ran through all java/lang/ProcessBuilder
> jtreg tests ok.
>
> Thanks, Thomas
>
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