bugmake - Bugs: bug #51159, pselect jobserver stuck at read...


bug #51159: pselect jobserver stuck at read does not reap children

Submitter:  Koen Van Hoof <kvho>
Submitted:  Fri 02 Jun 2017 10:44:13 AM UTC
Severity:  3 - Normal Item Group:  Bug
Status:  Fixed Privacy:  Public
Assigned to:  psmith Open/Closed:  Closed
Component Version:  4.2.1 Operating System:  POSIX-Based
Fixed Release:  4.3 Triage Status:  None
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Sun 04 Jun 2017 11:04:26 PM UTC, comment #3: 

I actually didn't notice the patch attached here before I created a fix since I didn't scroll down far enough (my bad), but the fix I wrote is more-or-less equivalent, although with some extras.

A fix has been pushed and will be in the next release.  Thank you for filing a report!

Paul D. Smith <psmith>
Group administrator
Fri 02 Jun 2017 05:36:41 PM UTC, comment #2: 

This does look like a promising diagnosis.  I'll look at it this weekend.

Paul D. Smith <psmith>
Group administrator
Fri 02 Jun 2017 03:43:09 PM UTC, comment #1: 

Is this part of:

bug #49014: Zombies in parallel builds with pselect code

But with the key missing ingredient - a diagnosis - and a fix?

Martin Dorey <mdorey>
Fri 02 Jun 2017 10:44:13 AM UTC, original submission:  

When using parallel recurse make, several child make processes will  be waiting in pselect.
When some make is writing a token in the pipe, several of these processes will leave the pselect, and trying to read the pipe.
Only 1 will actually get the token.  All others will be blocked in the read.
Eventually tokens will be written to the pipe, unblocking these make processes.

Solution : make the pipe non blocking, in order for all the processes that miss the token to call pselect again.

Koen Van Hoof <kvho>


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Attach Files:

Attached Files
file #40839:  patch added by kvho (902B - application/octet-stream)


Depends on the following items: None found

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    Follow 5 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2017-06-04 psmith StatusNone Fixed
        Assigned toNone psmith
        Open/ClosedOpen Closed
        Fixed ReleaseNone 4.3
    2017-06-02 kvho Attached File- Added patch, #40839

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