Graham,
You placed the fix in a better spot than I did. I had placed it after the
apr_pool_userdata stuff due to not understanding what that was all about.
It makes better sense to simply test and exit the python_init() routine as
quickly as possible in the Win32 parent process. Your comment is good, too.
I will test your version and confirm.
Thanks!
Jeff
----- Original Message -----
From: "Graham Dumpleton" <[EMAIL PROTECTED]>
To: "Jeff Robbins" <[EMAIL PROTECTED]>
Cc: "python-dev list" <python-dev@httpd.apache.org>
Sent: Wednesday, November 08, 2006 05:38
Subject: Re: MODPYTHON-195
On 07/11/2006, at 10:51 PM, Jeff Robbins wrote:
Graham,
The problem on Win32 is that (I believe) we never want to initialize
Python in the persistent parent process. All the web action is in the
child process which is long-lived and it is this child process that
maintains the thread pool which services web requests.
FWIW, in UNIX the initialisation of Python in the parent process is a
good thing
as it means it is only done once no matter how many child processes there
are. This is because child processes are created as a fork of the parent
process
and so they inherit the already initialised Python interpreter, thereby
meaning
initialisation of the child process is quicker.
Since Win32 doesn't have an equivalent of fork, when the child process
is created the full Python initialisation is done anyway. Thus avoiding
the
initialisation of Python in the parent is probably reasonable.
The parent process as far as I can tell sits there to support restarting
the child process and support the Win32 Service Control Manager (SCM)
which has a protocol for how a process must respond to certain messages
in order to be a service on Win32.
I do not know how to use flags alone to distinguish the two processes.
The code I put in is not trying to restrict a call to python_init() to
only happen once in the parent process. It is preventing python_init()
from initializing Python in the parent process.
I hope this clarifies things somewhat.
I want to note here that mpm_winnt.c line 1108 looks like this:
/* AP_PARENT_PID is only valid in the child */
pid = getenv("AP_PARENT_PID");
if (pid)
{
/* This is the child */
This environmental is how it knows to run certain code only in the child
process.
In summary,
if we do not want to run python_init() in the special Win32 parent
process, we need a way to distinguish this parent process from the child
process in which we DO want to run python_init(). The code which
maintains this dual process architecture (undoubtedly in support of the
Win32 service architecture) uses an environmental that it purposefull
creates and injects into the child process "AP_PARENT_PID". I don't see
how we can do better than use this same distinguishing characterisic to
know not to run python_init() in the parent process.
As it stands I just may have to take you word on this as I don't have
first hand
access to Win32 platform (and don't want to) to experiment. The
AP_PARENT_PID
environment variable is at least present in all Apache 2.0 and 2.2
versions that
we support, so at least okay for a while if we rely on that. In the
future, if Apache
changes this, we will just need to accommodate any new/official way of
determining
it.
Anyway, is the following what you are expecting and is it placed where
you expect
it within the python_init() function?
static int initialized = 0;
#ifdef WIN32
/* No need to run python_init() in Win32 parent processes as
* the lack of fork on Win32 means we get no benefit as far as
* inheriting a preinitialized Python interpreter. Further,
* upon a restart on Win32 platform the python_init() function
* will be called again in the parent process but without some
* resources allocated by the previous call having being
* released properly, resulting in memory and Win32 resource
* leaks.
*/
if (!getenv("AP_PARENT_PID"))
return OK;
#endif /* WIN32 */
apr_pool_userdata_get(&data, userdata_key, s->process->pool);
if (!data) {
apr_pool_userdata_set((const void *)1, userdata_key,
apr_pool_cleanup_null, s->process->pool);
return OK;
}
Graham
