IDS Forum

Re: IFX_XFER_SHMBASE

Posted By: Andreas Legner
Date: Monday, 14 March 2016, at 6:16 a.m.

In Response To: Re: IFX_XFER_SHMBASE (BillHatVerizon)

Hi Bill,

this might be less of a memory management issue within IDS and a shared=20
library problem rather. Maybe some OS or Informix DLL gets located /=20
loaded at a memory location that's in the way of more contiguous shared=20
memory allocation.

You might be able to determine such 'misplaced' DLL by locating the oninit =

process in Process Explorer (from MS -> Sysinternals) and looking at DLLs=20
(Ctrl-D or View -> Lower Pane View -> DLLs). In this view you'd first=20
have to select more columns to display, what you need is the 'Base' column =

(and maybe also the 'Image Base' column). Now sort this view by 'Base'=20
column and compare the output to 'onstat -g seg' output. The later should =

have your shared memory segments as a contiguous set of memory ranges=20
(addr + size -> next addr), of which you'd find the upper end by adding=20
last segment's size (decimal) to its addr (hex).. Now you'd look at=20
oninit's DLL view again and find a DLL with a Base address closly above=20
this value. If there is one, this would be the reason why you can't=20
allocate more shared memory to this server.

In case you were able to determine such badly placed DLL this is where=20
'Image Base' comes into play. Image base is where the DLL itself says=20
it's to be placed, and I'd expect this to be the same value as the bad=20
'Base' address. If a DLL gets loaded and can be loaded at its imprinted=20
Image Base, this is what's going to occur, otherwise it would be loaded at =

a different location. So no problem if the DLL got loaded after shared=20
memory alread yhad been allocated. In Informix, on the other hand, shared =

memory allocation might occur only after certain DLLs have been loaded by=20
oninit.exe in which case shared memory creation might draw the short=20
straw.
Long story short: there's a circumvention to this problem by simply=20
're-basing' such DLL, i.e. modifying its imprinted base address to=20
something more suitable.
But let's first determine if this really is what's in your way.

There also is http://www.ibm.com/support/docview.wss?uid=3Dswg21389180 on=20
Informix on 32bit Windows in general which also touches a bit on this=20
particular problem.

Regards,

Andreas Legner, Informix L2 support

From: "BillHatVerizon" <garage=5Fdba@verizon.net>
To: ids@iiug.org
Date: 12.03.2016 03:06
Subject: Re: IFX=5FXFER=5FSHMBASE [36732]
Sent by: ids-bounces@iiug.org

Thanks to all that answered.=20
The solution was to change this:=20

BUFFERPOOL=20
size=3D4K,buffers=3D100000,lrus=3D16,lru=5Fmin=5Fdirty=3D20.00,lru=5Fmax=5F=
dirty=3D30.00=20
BUFFERPOOL=20
size=3D16K,buffers=3D20000,lrus=3D8,lru=5Fmin=5Fdirty=3D20.00,lru=5Fmax=5Fd=
irty=3D30.00=20

to this:=20
BUFFERPOOL size=3D4K,start=5Fmemory=3D200mb,memory=3D400mb=20
BUFFERPOOL size=3D16K,start=5Fmemory=3D120mb,memory=3D320mb=20

Somehow the memory management in ids failed.=20
The ids =E2??working set=E2?=9D memory in Windows task manager went from ab=
out=20
850mb=20
down to 426mb.=20
The shared memory is limited to 2GB on this version, so I don=E2??t=20
understand=20
why onstat, ontape, etc blow up in this situation. They worked until TC4=20
(with=20
working set pushing the 2GB mark )=20
From: "WOLFGANG EPPLER" <wolfgang.eppler@de.ibm.com>=20
Date: March 7, 2016 at 9:54:29 AM CST=20
To: ids@iiug.org=20
Subject: Re: IFX=5FXFER=5FSHMBASE [36711]=20
Reply-To: ids@iiug.org=20

Probably you installed something before the problem started.=20
Maybe a new/updated driver, windows updates, ...=20

As another comment already mentioned, you can use Process Explorer to find =

out=20
why onstat cannot attach to shared memory.=20
You need the 'lower pane' view and configure it to display DLLs.=20

For the failing process you should find a DLL with a base address in the=20
middle of the process address space used by Informix.=20
You can calculate the address space used by Informix by selecting from=20
sysmaster:syssegments to identify the start address for memory segments=20
(seg=5Fshmaddr) and its sizes (seg=5Fsize).=20

Generally, why do you use 12.10.TC4 which is 32-bit Informix ?=20
This limits memory available for Informix to 2.7 GB.=20
And makes MapViewOfFileEx problems much more likely.=20

By the way, for onstat you cannot use IFX=5FXFER=5FSHMBASE, so this is not =
an=20
option here.=20

***************************************************************************=
****=20

Forum Note: Use "Reply" to post a response in the discussion forum.=20

***************************************************************************=
****=20

Forum Note: Use "Reply" to post a response in the discussion forum.=20

Messages In This Thread

• IFX_XFER_SHMBASE
  BillHatVerizon -- Monday, 29 February 2016, at 11:04 a.m.
  • RE: IFX_XFER_SHMBASE
    Mike Walker -- Monday, 29 February 2016, at 11:34 a.m.
    • Re: IFX_XFER_SHMBASE
      BillHatVerizon -- Monday, 29 February 2016, at 11:52 a.m.
      • Re: IFX_XFER_SHMBASE
        BRYCE STENBERG -- Monday, 29 February 2016, at 4:15 p.m.
        • Re:IFX_XFER_SHMBASE
          BillHatVerizon -- Tuesday, 1 March 2016, at 11:47 p.m.
  • Re: IFX_XFER_SHMBASE
    WOLFGANG EPPLER -- Monday, 7 March 2016, at 10:54 a.m.
    • Re: Fwd: IFX_XFER_SHMBASE
      BillHatVerizon -- Monday, 7 March 2016, at 4:16 p.m.
      • Re: Fwd: IFX_XFER_SHMBASE
        WOLFGANG EPPLER -- Tuesday, 8 March 2016, at 4:35 a.m.
    • Re: IFX_XFER_SHMBASE
      BillHatVerizon -- Friday, 11 March 2016, at 8:50 p.m.
      • Re: IFX_XFER_SHMBASE
        Andreas Legner -- Monday, 14 March 2016, at 6:16 a.m.

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