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#359 re-entrant Tcl_Finalize()

closed-accepted
Don Porter
02. Event Loops (3)
5
2004-07-30
2004-07-28
Don Porter
No

This patch moves the ExitHandler calls
of Tcl_Finalize() outside of the
TclpInitLock-ed region.

This will avoid deadlocks like the one
seen in Tk Bug 714956, when the
execution of a registered ExitHandler
causes another, nested, call to
Tcl_Finalize().

This patch should be safe, because
the exitHandler loop is careful to always
pull the next handler to run from the
beginning of the loop, and discard each
as it is run, terminating only when the
list is empty.

The rest of Tcl_Finalize(), protected
by a TclpInitLock region, should, we
hope, be prevented from making
a nested call back into Tcl_Finalize().

Please review.

Discussion

  • Don Porter

    Don Porter - 2004-07-28
     
    finalize.patch

  • Don Porter

    Don Porter - 2004-07-28
    • assigned_to: hobbs --> vasiljevic
     

  • Don Porter

    Don Porter - 2004-07-28

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    passing on to someone I think
    knows Tcl_Finalize() better.

    This patch fixes a bug, but does
    it cause any new trouble?

     

  • Zoran Vasiljevic

    Zoran Vasiljevic - 2004-07-29

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    I see no obvious problems.
    A side-effect, though, is that, when Tcl_Finalize is called
    simultaneously by two threads, both of them will execute
    exit callbacks. Each exit callback will be run once, but you
    never know in which thread this may happen.
    Strictly speaking, this should pose no problems, provided that
    exit callbacks are really app-wide and do not assume any
    thread local storage ownerships and such. Actually, they should
    be designed as such in the first place.

     

  • Don Porter

    Don Porter - 2004-07-30

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    Thanks! Applying for 8.4.8 and 8.5.

     

  • Don Porter

    Don Porter - 2004-07-30
    • assigned_to: vasiljevic --> dgp
    • status: open --> closed-accepted