Announcement

#2 · 01-20-05, 10:10 AM

RE: [mrc] Bug In Miva Engine or just Scripting Error

Hi Darren,

I've seen two things in scrips cause an "engine crash".
Neither are actually engine crashes as you'll see below
and only the first could really be attributed to a bug
in the script.

1) Infinite loop / deadlock. The infinite loop condition
can be caused by any number of programming errors, and
deadlock can occur with lockfiles. Both can cause the
server to issue a Server 500 error if the server timeout
is shorter than the engine timeout. (though recently I've
seen the engine stop processing and display an error code
if it thinks it has detected a deadlock)

2) Significant memory consumption. If a script uses up
too much memory, the web server may kill the engine. Most
common on hosts that artificially limit the process size.
This will also cause a Server 500 error.

Other than this, nothing you do in Miva Script should
cause a server crash. In theory. :) Now, I *have* seen
instances where incorrect token/template code caused
an infinite loop, leading the store owner and/or host
to "blame" the module that allows template/token code.
But again, that's not a module bug, it's just a danger
of having interpreted code that a customer can modify.

Regards,
James

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Darren
Sent: Thursday, January 20, 2005 12:52 PM
To: [email protected]; [email protected];
[email protected]
Subject: [mrc] Bug In Miva Engine or just Scripting Error

I'm getting sick and tired of having my scripts being blamed for crashes in
the Miva Empresa for Windows engine.

Can ANYONE show me any MivaScript that when coded improperly should cause
the engine to crash? Obviously, there must be SOMETHING that I'm doing in
my MivaScript that regularly can cause the Miva Engine to crash (at least
the Windows version), and is documented somewhere as being something NOT to
do.....but I cannot find anything listed anywhere.

I know in C/C++ you have pointers....lots of room to do things wrong and
crash, but I just cannot find any such language constructs in MivaScript.
But, since Miva Support and Development Staff continually "pass-the-buck" by
blaming me, I thought I would finally solicit information from other
MivaScripts users...because obviously I'm missing something here.

Thanks for your time.

Darren Ehlers
OpenUI Developer Consortium
<A HREF ="http://www.openui.org/">http://www.openui.org/</A>

#3 · 01-20-05, 10:18 AM

Bug In Miva Engine or just Scripting Error

Darren,

I assume you're using uncompiled? I had some issues with the engine =
crashing
because of my code; however I don't remember exactly what caused it (I =
think
it might have been a loop or something, don't know). I'll see if I can =
find
any example.

I've been using the VM ever since it came out, so I don't use uncompiled =
any
more. Haven't had those problems since the old empresa days.

But I know that bad code CAN cause the engine to crash (of course it =
doesn't
mean that is the problem).

HTH,

Ben

-----Original Message-----
From: [email protected] [mailto:[email protected]] On =
Behalf
Of Darren
Sent: Thursday, January 20, 2005 11:52 AM
To: [email protected]; [email protected];
[email protected]
Subject: [meu] Bug In Miva Engine or just Scripting Error

I'm getting sick and tired of having my scripts being blamed for crashes =
in
the Miva Empresa for Windows engine.

Can ANYONE show me any MivaScript that when coded improperly should =
cause
the engine to crash? Obviously, there must be SOMETHING that I'm doing =
in
my MivaScript that regularly can cause the Miva Engine to crash (at =
least
the Windows version), and is documented somewhere as being something NOT =
to
do.....but I cannot find anything listed anywhere.

I know in C/C++ you have pointers....lots of room to do things wrong and
crash, but I just cannot find any such language constructs in =
MivaScript.
But, since Miva Support and Development Staff continually =
"pass-the-buck" by
blaming me, I thought I would finally solicit information from other
MivaScripts users...because obviously I'm missing something here.

Thanks for your time.

Darren Ehlers
OpenUI Developer Consortium
<A HREF ="http://www.openui.org/=20">http://www.openui.org/=20</A>

#4 · 01-20-05, 10:25 AM

Bug In Miva Engine or just Scripting Error

Nope, using compiled....but it's the same issue that has been going on for
4-5 years with Miva Empresa for Windows. When put under any load, it seems
to just croak.

And you say that bad code can cause the engine to crash....do you have any
examples?

Darren

> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Ben Walsh
> Sent: Thursday, January 20, 2005 12:18 PM
> To: [email protected]; [email protected];
> [email protected]
> Subject: RE: [meu] Bug In Miva Engine or just Scripting Error
>
>
> Darren,
>
> I assume you're using uncompiled? I had some issues with the
> engine crashing because of my code; however I don't remember
> exactly what caused it (I think it might have been a loop or
> something, don't know). I'll see if I can find any example.
>
> I've been using the VM ever since it came out, so I don't use
> uncompiled any more. Haven't had those problems since the old
> empresa days.
>
> But I know that bad code CAN cause the engine to crash (of
> course it doesn't mean that is the problem).
>
> HTH,
>
> Ben
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Darren
> Sent: Thursday, January 20, 2005 11:52 AM
> To: [email protected]; [email protected];
> [email protected]
> Subject: [meu] Bug In Miva Engine or just Scripting Error
>
> I'm getting sick and tired of having my scripts being blamed
> for crashes in the Miva Empresa for Windows engine.
>
> Can ANYONE show me any MivaScript that when coded improperly
> should cause the engine to crash? Obviously, there must be
> SOMETHING that I'm doing in my MivaScript that regularly can
> cause the Miva Engine to crash (at least the Windows
> version), and is documented somewhere as being something NOT
> to do.....but I cannot find anything listed anywhere.
>
> I know in C/C++ you have pointers....lots of room to do
> things wrong and crash, but I just cannot find any such
> language constructs in MivaScript. But, since Miva Support
> and Development Staff continually "pass-the-buck" by blaming
> me, I thought I would finally solicit information from other
> MivaScripts users...because obviously I'm missing something here.
>
> Thanks for your time.
>
> Darren Ehlers
> OpenUI Developer Consortium
> <A HREF ="http://www.openui.org/ ">http://www.openui.org/ </A>
>
>
>
>

#5 · 01-20-05, 11:27 AM

Bug In Miva Engine or just Scripting Error

It is possible (or at least was) to crash the engine using
just MivaScript. I haven't run across anything lately that
would crash it, but I'm sure bugs are still out there.

One example I came across (and mind you this was 2-3 years
ago so I forgot all the fine details) was in <MvDO>. It has
to deal with trying to <MvDO> a function in the file you're
running. So if you were running main.mv and tried to:
<MvDO FILE="main.mv" NAME="l.date"
VALUE="{showdate(s.time_t)}">
it would cause a crash. There were other factors involved
but that was the crux.

Another dealt with nested functions where one was a
built-in and one was user defined. So something like:
<MvEVAL EXPR="{ gettoken(get_username(users.d.name), " ",
1) }"> Once again, I think there was one other factor
involved but it escapes me.

These were offical "Scott Bugs". Stuff that only I could
have found due to odd programming habits and dumb luck.

So yes, it is/was possible to crash the engine using
nothing but correctly written MivaScript. Now it's just a
matter of tracking down what your scripts are doing and
reducing it down to reach the one line of code that's
causing headaches.

/ScottMc

--- Ben Walsh <[email protected]> wrote:

> Darren,
>
> I assume you're using uncompiled? I had some issues with
> the engine crashing
> because of my code; however I don't remember exactly what
> caused it (I think
> it might have been a loop or something, don't know). I'll
> see if I can find
> any example.
>
> I've been using the VM ever since it came out, so I don't
> use uncompiled any
> more. Haven't had those problems since the old empresa
> days.
>
> But I know that bad code CAN cause the engine to crash
> (of course it doesn't
> mean that is the problem).
>
> HTH,
>
> Ben
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf
> Of Darren
> Sent: Thursday, January 20, 2005 11:52 AM
> To: [email protected]; [email protected];
> [email protected]
> Subject: [meu] Bug In Miva Engine or just Scripting Error
>
> I'm getting sick and tired of having my scripts being
> blamed for crashes in
> the Miva Empresa for Windows engine.
>
> Can ANYONE show me any MivaScript that when coded
> improperly should cause
> the engine to crash? Obviously, there must be SOMETHING
> that I'm doing in
> my MivaScript that regularly can cause the Miva Engine to
> crash (at least
> the Windows version), and is documented somewhere as
> being something NOT to
> do.....but I cannot find anything listed anywhere.
>
> I know in C/C++ you have pointers....lots of room to do
> things wrong and
> crash, but I just cannot find any such language
> constructs in MivaScript.
> But, since Miva Support and Development Staff continually
> "pass-the-buck" by
> blaming me, I thought I would finally solicit information
> from other
> MivaScripts users...because obviously I'm missing
> something here.
>
> Thanks for your time.
>
> Darren Ehlers
> OpenUI Developer Consortium
> <A HREF ="http://www.openui.org/ ">http://www.openui.org/ </A>
>
>
>
>

#6 · 01-20-05, 12:01 PM

Bug In Miva Engine or just Scripting Error

Hi Darren,

Frankly I am quite "happy" to hear that I am not the only one who manages to
crash the engine with regular Mivascripts.

On Linux or FreeBSD I never experienced any stability problems for identical
scripts like I do on my Windows servers (Win2000 and Win2003, both on IIS 5
and 6). What is extremely annoying now is that after 4 or 5 repeated crashes
of EmpresaVM, IIS6 shuts Empresa off, basically requiring a manual restart
of IIS. Of course as a security measure that is probably a good thing.

I tend to attribute most of these crashes to filesystem issues relating to
packing and locking. I also know that Empresa -sometimes- crashes on some
array functions (miva_array_deserialize() when there are over 12.500
(approx.) array members), and it choke so badly on some scripts that used
glosub array that I actually never used it anymore. It's possible that this
has been fixed since.

miva_array_deserialize() never had any problems on *nix.

I have a few scripts that can run for several hours, and here, too, the
engine occassionally simply dies without any further notice (or entry into
Wins event log). Since Mivascript was never truly designed for these kind of
things, I did not consider this as a big problem (as a matter of fact it is
quite impressive that the old lady -Empresa- handles some of those long
running things so well). A simple workaround is to break the long task into
smaller tasks that automatically call the next one, even though the
undelying problem might still persist.

I suspected memory issues, but there was nothing really worrysome to observe
during runtime of these scripts (enough memory, no strange leaks etc). Even
MivaMia handled really large amounts of memory quite well (>1GB) when even
my mouse wouldn't move anymore.

Markus

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Darren
Sent: Thursday, January 20, 2005 12:52 PM
To: [email protected]; [email protected];
[email protected]
Subject: [meu] Bug In Miva Engine or just Scripting Error

I'm getting sick and tired of having my scripts being blamed for crashes in
the Miva Empresa for Windows engine.

Can ANYONE show me any MivaScript that when coded improperly should cause
the engine to crash? Obviously, there must be SOMETHING that I'm doing in
my MivaScript that regularly can cause the Miva Engine to crash (at least
the Windows version), and is documented somewhere as being something NOT to
do.....but I cannot find anything listed anywhere.

I know in C/C++ you have pointers....lots of room to do things wrong and
crash, but I just cannot find any such language constructs in MivaScript.
But, since Miva Support and Development Staff continually "pass-the-buck" by
blaming me, I thought I would finally solicit information from other
MivaScripts users...because obviously I'm missing something here.

Thanks for your time.

Darren Ehlers
OpenUI Developer Consortium
<A HREF ="http://www.openui.org/ ">http://www.openui.org/ </A>

#7 · 01-20-05, 12:15 PM

Bug In Miva Engine or just Scripting Error

I believe Darren's post went misunderstood or misinterpreted. There are
certainly many bugs in diverse versions of Miva Empresa, that can cause the
engine to crash, but Darren is not a newbie that he wouldn't know that.
Darren reported himself some of them that passed through this list. He would
be easily able to work around the bugs. Darren's point was that in Miva
Script there is no way to programmatically cause the engine to crash through
bad or too resource intensive coding. If it happens, it is Empresa who
failed, not the script.

Certainly, Miva Script can be written poorly, insecure, inefficient, slow,
resource-hungry, but that's still not a reason for the Empresa to crash.
Unlike at other languages, Miva Script _syntax_ does not let any possibility
to crash the engine deliberately, whatever you try to write. Other languages
can be crushed for example through improper use of pointers, (like Darren
mentioned), or direct memory, IRQ or BIOS operations in many other
languages), but there is nothing like that that could not be handled by
Empresa.

So yes, you can crash Empresa, but only through hitting an Empresa bug. If
Empresa does not handle exceptions like low memory cleanly, it is certainly
not a fault of the concerned Miva Script. Sure, it is better to write
applications using as few resources as possible, but if they need more, the
engine must either response with an error, or process them. If it crashes,
it is an Empresa bug, not a Miva Script bug.

Not to blame solely Miva Empresa, the fault may be also in layers below it
(Web server, C libraries, OS, BIOS). Especially if the problem happens
exclusively on certain platforms, there is some chance the bug is not in
Empresa but rather elsewhere. Honestly told, I would rather expect the
problem at the specific Empresa build in such case, though :)

Ivo Truxa

| http://miva.truxoft.com
| Advanced Miva Merchant modules

-----Original Message-----
From: Scott McC

It is possible (or at least was) to crash the engine using
just MivaScript. I haven't run across anything lately that
would crash it, but I'm sure bugs are still out there.

One example I came across (and mind you this was 2-3 years
ago so I forgot all the fine details) was in <MvDO>. It has
to deal with trying to <MvDO> a function in the file you're
running. So if you were running main.mv and tried to:
<MvDO FILE="main.mv" NAME="l.date"
VALUE="{showdate(s.time_t)}">
it would cause a crash. There were other factors involved
but that was the crux.

Another dealt with nested functions where one was a
built-in and one was user defined. So something like:
<MvEVAL EXPR="{ gettoken(get_username(users.d.name), " ",
1) }"> Once again, I think there was one other factor
involved but it escapes me.

These were offical "Scott Bugs". Stuff that only I could
have found due to odd programming habits and dumb luck.

So yes, it is/was possible to crash the engine using
nothing but correctly written MivaScript. Now it's just a
matter of tracking down what your scripts are doing and
reducing it down to reach the one line of code that's
causing headaches.

/ScottMc

--- Ben Walsh <[email protected]> wrote:

> Darren,
>
> I assume you're using uncompiled? I had some issues with
> the engine crashing
> because of my code; however I don't remember exactly what
> caused it (I think
> it might have been a loop or something, don't know). I'll
> see if I can find
> any example.
>
> I've been using the VM ever since it came out, so I don't
> use uncompiled any
> more. Haven't had those problems since the old empresa
> days.
>
> But I know that bad code CAN cause the engine to crash
> (of course it doesn't
> mean that is the problem).
>
> HTH,
>
> Ben
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf
> Of Darren
> Sent: Thursday, January 20, 2005 11:52 AM
> To: [email protected]; [email protected];
> [email protected]
> Subject: [meu] Bug In Miva Engine or just Scripting Error
>
> I'm getting sick and tired of having my scripts being
> blamed for crashes in
> the Miva Empresa for Windows engine.
>
> Can ANYONE show me any MivaScript that when coded
> improperly should cause
> the engine to crash? Obviously, there must be SOMETHING
> that I'm doing in
> my MivaScript that regularly can cause the Miva Engine to
> crash (at least
> the Windows version), and is documented somewhere as
> being something NOT to
> do.....but I cannot find anything listed anywhere.
>
> I know in C/C++ you have pointers....lots of room to do
> things wrong and
> crash, but I just cannot find any such language
> constructs in MivaScript.
> But, since Miva Support and Development Staff continually
> "pass-the-buck" by
> blaming me, I thought I would finally solicit information
> from other
> MivaScripts users...because obviously I'm missing
> something here.
>
> Thanks for your time.
>
> Darren Ehlers
> OpenUI Developer Consortium
> <A HREF ="http://www.openui.org/ ">http://www.openui.org/ </A>
>
>
>
>

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