[ naviserver-Feature Requests-1241351 ] Allocate single interp per-server per-thread

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Feature Requests item #1241351, was opened at 2005-07-20 00:02
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Stephen Deasey (sdeasey)
Assigned to: Stephen Deasey (sdeasey)
Summary: Allocate single interp per-server per-thread

Initial Comment:

When some C code want to run some Tcl code it first
calls Ns_TclAllocateInterp(server) to get an interp. 
Interps are de-allocated and cached per-thread
(per-server) for the next allocation.

If there is no cached interp, a new one is created. 
This can also happen when there was a cached interp but
it has already been allocated.  Recursive allocation
can happen e.g. when a script registered with
ns_register_proc (which allocates an interp to run the
script) calls the command ns_pagepath (which may
allocate an interp to run a registered Tcl callback).

Then end result is that more than one interps
per-thread per-server can be allocated, the number
depending on the ammount of recursion due to Tcl
callbacks.  This is bad from a memory point of view and
a speed point of view as interp traces run each time an
interp is allocated.

Attached is a patch which implements reference counting
on NsInterp structures.  Interps are only allocated
fresh if no interp has yet been allocated for that
thread.  If an interp has already been allocated, the
reference count is incremented.  The refcnt is
decremented on de-allocation untill all references are
released, and then interp traces and cleanups etc. are run.



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