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    SubjectRe: [PATCH] prctl: add PR_{SET,GET}_CHILD_REAPER to allow simple process supervision
    On Fri, 29 Jul 2011 02:01:44 +0200
    Kay Sievers <kay.sievers@vrfy.org> wrote:

    > From: Lennart Poettering <lennart@poettering.net>
    > Subject: prctl: add PR_{SET,GET}_CHILD_REAPER to allow simple process supervision
    >
    > Userspace service managers/supervisors need to track their started
    > services. Many services daemonize by double-forking and get implicitely
    > re-parented to PID 1. The process manager will no longer be able to
    > receive the SIGCHLD signals for them.
    >
    > With this prctl, a service manager can mark itself as a sort of
    > 'sub-init' process, able to stay as the parent process for all processes
    > created by the started services. All SIGCHLD signals will be delivered
    > to the service manager.
    >
    > As a side effect, the relevant parent PID information does not get lost
    > by a double-fork, which results in a more elaborate process tree and 'ps'
    > output.
    >
    > This is orthogonal to PID namespaces. PID namespaces are isolated
    > from each other, while a service management process usually requires
    > the serices to live in the same namespace, to be able to talk to each
    > other.
    >
    > Users of this will be the systemd per-user instance, which provides
    > init-like functionality for the user's login session and D-Bus, which
    > activates bus services on on-demand. Both will need init-like capabilities
    > to be able to properly keep track of the services they start.
    >

    Interesting patch. I can't immediately see any nasty effects from it..

    Did you consider using the existing taskstats capability for this?

    The comment block over find_new_reaper() is now incomplete. Please
    update it?

    prctl(2) has a manpage. What's the plan for updating it?



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