Java MapScript issues Servlet

Sean Gillies sgillies at FRII.COM
Tue Mar 1 09:32:16 PST 2005 

Joe,

Make sure to clean up the existing .obj files, sometimes we all forget 
this.  If you did, nevermind :)

As soon as you can start to isolate the problems, enter them into 
MapServer's bugzilla

     http://mapserver.gis.umn.edu/bugs/enter_bug.cgi

under the Mapscript-SWIG component.  That's the best way for us to team 
up on the bugs.

cheers,
Sean

On Mar 1, 2005, at 10:19 AM, Miller Joseph wrote:

> Thanks Sean.  When you say defined I'm assuming that you mean that a 
> variable equal to
>
> "-DUSE_THREAD" should be included as one of the MS_DEFS at the end of 
> the nmake.opt file?  I did that and the build seemed to run fine.  If 
> that is all I need to do, then I am still having memory problems that 
> I will pass on to Umberto<sigh>.
>
> Joe Miller
>
> From: Sean Gillies [mailto:sgillies at frii.com]
> Sent: Tue 3/1/2005 9:32 AM
> To: Miller Joseph
> Cc: MAPSERVER-USERS at LISTS.UMN.EDU
> Subject: Re: Java MapScript issues Servlet
>
>
> Joe,
>
> You do have the option to turn on thread safety, it's just that 
> nmake.opt is incomplete.  Its authors are not multi-threading users.  
> Make sure that the USE_THREAD macro is defined when compiling 
> mapthread.c.  It's as simple as that.
>
> cheers,
> Sean
>
> On Feb 28, 2005, at 8:41 PM, Miller Joseph wrote:
>
> > This is a multi-part message in MIME format.
> >
> > ------_=_NextPart_001_01C51E11.40BE0E8D
> > Content-Type: text/plain;
> >         charset="iso-8859-1"
> > Content-Transfer-Encoding: quoted-printable
> >
> > To All,
> > Umberto and Mario are correct about the problems I've had.  They are 
> =
> > definitely related to the lack of thread safety in my mapscript.dll 
> > that =
> > I built using MS Visual C tools.  Can anyone tell me why I don't 
> have =
> > the option to turn on thread safety in nmake.opt (unlike in *Nix 
> > flavors =
> > of the build option files)?  Was it an oversight, future feature or =
> > excluded because it is included by default whenever mapserver is 
> built 
> > =
> > in Windows and there is no need to turn it off?
> > =20
> > Thanks,
> > Joe Miller
> >
> > ________________________________
> >
> > From: UMN MapServer Users List on behalf of Umberto Nicoletti
> > Sent: Mon 2/28/2005 10:31 AM
> > To: MAPSERVER-USERS at LISTS.UMN.EDU
> > Subject: Re: [UMN_MAPSERVER-USERS] Java MapScript issues Servlet
> >
> >
> >
> > Quoting "Mario H. Basa" <mhbasa at YAHOO.COM>:
> >
> >> Hi.
> >>
> >>> From my experience, Java Mapscript still has some
> >> problems with threads, and can still easily bring down
> >> Tomcat even with the thread compile option is set.
> >> Please correct me if I am wrong.
> >>
> >
> > Yes, that is probably correct, although it is not *that easy*. I 
> have =
> > also
> > stressed mapscript with jmeter and actually not found errors, but I 
> > did =
> > not
> > cover querying.
> > That is why I voted for improved thread safety when the devs showed =
> > their wishlists.
> >
> >
> >> What I did was I synchronized the class that does the
> >> map processing, and now my test app can survive
> >> benchmarking with JMeter. Here are my results as
> >> compared with a simillar PHP CGI program:
> >>
> >
> > This is definitely a correct workaround.
> >
> >> 4 threads (requests) per second, repeated 25 times
> >>
> >> PHP Mapscript 1.8 to 1.9 pages per second
> >> Java Mapscript 2.3 to 2.5 pages per second
> >>
> >> I was honestly surprised with the result and it is
> >> encouraging me to work with Java Mapscript even in a
> >> synchronized mode.
> >>
> >
> > Were you using apache 1.3 or 2.x in the php tests? Apache 1.3 uses a 
> =
> > fork based
> > model, that while being extremely safe and sound is not as fast as a 
> =
> > threaded
> > model. Apache 2.x has threads and should be faster.
> >
> > Regards,
> > Umberto
> >
> >> mario
> >> yokohama,japan
> >>
> >>
> >> --- Joseph Miller <miller_joseph at BAH.COM> wrote:
> >>
> >>> Umberto,
> >>>
> >>> 1)I don't think I compiled specifically with
> >>> multi-threading because it
> >>> wasn't an option listed in the nmake.opt for
> >>> Microsoft Visual C++  options
> >>> file???  The last I heard multithreading was not
> >>> even on the horizon for
> >>> mapserver and yet I see it in the Unix build options
> >>> file?  What do I need
> >>> to do this?
> >>>
> >>> 2)I tried both options you mentioned, I had the
> >>> problem when passed the
> >>> same mapObj from request to request and stored it in
> >>> the session and when I
> >>> set it to null after every request and instantiated
> >>> it and assigned
> >>> attributes based on other variables stored in the
> >>> requests and sessions?
> >>> I'm assuming the latter is preferred?
> >>>
> >>> Thanks,
> >>> Joe Miller
> >>>
> >>> On Mon, 28 Feb 2005 09:44:21 +0100, Umberto
> >>> Nicoletti
> >>> <unicoletti at PROMETEO.IT> wrote:
> >>>
> >>>> Did you enable threads support?
> >>>> Java, and especially servlets, are definitely
> >>> highly concurrent
> >>>> environment, so you have to enable thread support
> >>> when compiling
> >>>> mapserver and mapscript. One very problematic spot
> >>> with regards to
> >>>> threads is in fact the parser of .map files.
> >>>>
> >>>> Do you attempt to reuse the same mapObj across
> >>> multiple requests or just
> >>>> create one and dispose as soon as you are done
> >>> within a single request?
> >>>>
> >>>> HTH,
> >>>> Umberto
> >>>>
> >>>>
> >>>> On Mon, 2005-02-28 at 00:53 -0500, Miller Joseph
> >>> wrote:
> >>>>> Hi,
> >>>>> I'm having a baffling problem with a nightly
> >>> build of Java Mapscript
> >>>>> from about a month ago that I am running on
> >>> Windows 2000 with Tomcat
> >>>>> 5.5.4.
> >>>>>
> >>>>> The symptom I see is that I can generate the
> >>> default image but after the
> >>>>> fourth or fifth time that I pass a new envelope
> >>> to change the extent of
> >>>>> the image I get the following error:
> >>>>>
> >>>>> The relevant part of the stack trace:
> >>>>> java.lang.UnknownError: Failed to draw layer
> >>> named 'world'.
> >>>>>         at
> >>>
> >> edu.umn.gis.mapscript.mapscriptJNI.mapObj_draw(Native
> >>> Method)
> >>>>>         at
> >>> edu.umn.gis.mapscript.mapObj.draw(mapObj.java:397)
> >>>>>
> >>>>> Occasionally I'll get a flex scanner error or
> >>> tomcat will crash with an
> >>>>> Exception_Access_Violation memmove error similar
> >>> to the one referred to
> >>>>> here:
> >>>>>
> >>>
> >> =
> > http://forum.java.sun.com/thread.jspa?
> > forumID=3D52&messageID=3D1124599&th=
> > rea
> >>>>> dID=3D286832
> >>>>>
> >>>>> All of this happens whether I instatiate new
> >>> instances of the mapObj and
> >>>>> set everything to null or if I use the same
> >>> mapObj throughout and only
> >>>>> after a few passes, suggesting to me that there
> >>> is a memory issue
> >>>>> somewhere.  I can pass on some specific code, but
> >>> all I am really doing
> >>>>> is creating new envelopes to store extents and
> >>> then assigning them to
> >>>>> the mapObj or extracting the corner coordinates
> >>> and setting the extent
> >>>>> with them.
> >>>>>
> >>>>> I've been fighting this for a frustrating week
> >>> now.  Does anyone have
> >>>>> any advice?
> >>>>>
> >>>>> Thanks,
> >>>>> Joe Miller
> >>>> --
> >>>> Umberto Nicoletti
> >>> <Mercury> At that point it
> >>> will
> >>>> +390415701366   unicoletti at prometeo.it
> >>> compile, but segfault, as
> >>> it should..
> >>>> Prometeo S.R.L. The Software Experience
> >>>
> >>> Umberto,
> >>>
> >>> 1)I don't think I compiled specifically with
> >>> multi-threading because it
> >>> wasn't an option listed in the nmake.opt for
> >>> Microsoft Visual C++  options
> >>> file???  The last I heard multithreading was not
> >>> even on the horizon for
> >>> mapserver and yet I see it in the Unix build options
> >>> file?  What do I need
> >>> to do this?
> >>>
> >>> 2)I tried both options you mentioned, I had the
> >>> problem when passed the
> >>> same mapObj from request to request and stored it in
> >>> the session and when I
> >>> set it to null after every request and instantiated
> >>> it and assigned
> >>> attributes based on other variables stored in the
> >>> requests and sessions?
> >>> I'm assuming the latter is preferred?
> >>>
> >>> Thanks,
> >>> Joe Miller
> >>>
> >>
> >>
> >>
> >>
> >> __________________________________
> >> Do you Yahoo!?
> >> Yahoo! Sports - Sign up for Fantasy Baseball.
> >> http://baseball.fantasysports.yahoo.com/
> >>
> >
> --
> Sean Gillies
> sgillies at frii dot com
> http://users.frii.com/sgillies
>

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