Re: Retain dynamic shared memory segments for postmaster lifetime

Hello, I've managed to reconstruct windows build environment and
tried to run the previous patch.

====================
> >  - DSM implimentation seems divided into generic part (dsm.c) and
> >    platform dependent part(dsm_impl.c). This dsm_keep_segment
> >    puts WIN32 specific part directly into dms.c. I suppose it'd
> >    be better defining DSM_OP_KEEP_SEGMENT and calling dms_impl_op
> >    from dms_keep_segment, or something.
> >
> >  - Repeated calling of dsm_keep_segment even from different
> >    backends creates new (orphan) handles as many as it is called.
> >    Simplly invoking this function in some of extensions intending
> >    to stick segments might results in so many orphan
> >    handles. Something to curb that situation would be needed.
> 
> I think the right way to fix above 2 comments is as suggested by Robert.

Fine. I have no objection on that way.

> >  - "Global/PostgreSQL.%u" is the same literal constant with that
> >    occurred in dsm_impl_windows. It should be defined as a
> >    constant (or a macro).
> >
> >  - dms_impl_windows uses errcode_for_dynamic_shared_memory() for
> >    ereport and it finally falls down to
> >    errcode_for_file_access(). I think it is preferable, maybe.
> 
> Okay, will take care of these in new version after your verification
> on Windows.


I will apologize in advance for probably silly questions but I
have two problems.

====
Server was crashed by dsm_demo_read on my test environment but
unfortunately the cause is still uncertain for me.

| LOG:  server process (PID 19440) was terminated by exception 0xC0000005
| DETAIL:  Failed process was running: select dsm_demo_read(4294967297);
| HINT:  See C include file "ntstatus.h" for a description of the hexadecimal value.
| LOG:  terminating any other active server processes

0xC0000005 is ACCESS_VIOLATION. The crash occurred at aset.c:853

|  /* Try to allocate it */
|  block = (AllocBlock) malloc(blksize);

Where blksize is 55011304... It's sasier to investigate still
more if I could step into functions in the dynamic loaded module,
but VC2008 IDE skips over the function body:-( Do you have any
idea how I can step into there? My environment is VC2008 Express/
Win7-64. Step-into bounces back at the line where function
definition.

| PG_FUNCTION_INFO_V1(dsm_demo_create);


In contrast, dsm_demo_create doesn't crash and seems to return
sane vaule.

| =# select dsm_demo_create('hoge', 100);
|  dsm_demo_create
| -----------------
|       4294967297

===
And the another problem is perhaps not the issue of this module
but it happened for me.

| =# create extension dsm_demo;
| ERROR:  could not find function "dsm_demo_create" in file "c:/pgsql/lib/dsm_demo.dll"

I've found that generated dll file exports the function with the
names following after some investigation.

| ...\Debug>dumpbin /EXPORTS dsm_demo.dll
| Microsoft (R) COFF/PE Dumper Version 9.00.21022.08
| Copyright (C) Microsoft Corporation.  All rights reserved.
(snipped)
|           1    0 0001100A Pg_magic_func = @ILT+5(_Pg_magic_func)
|           2    1 00011118 pg_finfo_dsm_demo_create = @ILT+275(_pg_finfo_dsm_demo
| _create)
|           3    2 000110AF pg_finfo_dsm_demo_read = @ILT+170(_pg_finfo_dsm_demo_r

Then explicitly designating the function name in 'CREATE
FUNCTION' in dsm_demo--1.0.sql stops the complaint.  I might did
something wrong in setting up build environment for this dll but
I have no idea which would cause this kind of trouble..

| CREATE FUNCTION dsm_demo_create(pg_catalog.text, pg_catalog.int4 default 0)
| RETURNS pg_catalog.int8 STRICT
| AS 'MODULE_PATHNAME', 'pg_finfo_dsm_demo_create'
| LANGUAGE C;

Do you have any idea for this?

regards,

-- 
Kyotaro Horiguchi
NTT Open Source Software Center