First thread in proc in not passed to thread_dtor eventhandler upon exit

Hans Petter Selasky hps at
Sun Feb 19 08:44:09 UTC 2017

On 02/19/17 04:54, Konstantin Belousov wrote:
> On Sat, Feb 18, 2017 at 10:40:00PM +0100, Hans Petter Selasky wrote:
>> Hi,
>> Is the following a bug or feature. I observe that the first thread in a
>> procedure is not passed to thread_dtor as declared by the following
>> eventhandler, when the procedure exits.
>> EVENTHANDLER_DECLARE(thread_dtor, thread_dtor_fn);
>> Is this a bug or feature?
> This is a feature.  When a zombie process is reaped, the last thread in
> the process (the one which exited it) is left in the process thread list.
> This is an optimization, because process without at least one thread
> is never useful.
> You can see the code in fork1() which allocates struct proc from zone
> and then checks if there any thread pre-allocated as well (both struct
> proc and struct thread are type-stable).
> Since the last thread is not freed, its destructor is not signalled.

Hi Konstantin,

I see. To avoid leakage of LinuxKPI, Linux and Dtrace resources to all 
system threads, I think the attached patch is required. What do you 
think about the attached patch? If you don't like it can you suggest 
another approach?

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