<br><font size=2 face="sans-serif">Thank's Umberto. I did not know </font><font size=2><tt>-Xloggc</tt></font><font size=2 face="sans-serif">
before.</font>
<br>
<br><font size=2 face="sans-serif">As far as I understood </font><font size=2><tt>-Xloggc</tt></font><font size=2 face="sans-serif">
measures the memory allocated by the JVM.</font>
<br><font size=2 face="sans-serif">And this is the kind of memory which
is not hazardous ...</font>
<br>
<br><font size=2 face="sans-serif">Anyway I will look in this direction...</font>
<br>
<br><font size=2 face="sans-serif">Benedikt</font>
<br>
<br><font size=2><tt>Umberto Nicoletti <umberto.nicoletti@gmail.com>
schrieb am 29.06.2005 12:10:03:<br>
<br>
> On 6/29/05, Benedikt Rothe <umn-ms@hydrotec.de> wrote:<br>
> > <br>
> > Hello Umberto <br>
> > <br>
> > Thank you for yout hint's! <br>
> > <br>
> > You are right: One should be cautios. But for the moment I have
the<br>
> > impression <br>
> > that we seeme to have found a way, which don't raise obvious
errors in the<br>
> > first <br>
> > moment :-) <br>
> > <br>
> > After the mentioned changes in mapcopy.c the approache <br>
> > (TomCat/MapScript/Connection-Pooling/MapCloning) seeme to <br>
> > work for us. (Working with Version 4.6) <br>
> > <br>
> > But: <br>
> > - We do need some more stress-testing.(We already made automated
<br>
> > http-requests from a Java-Programs. But this was definitly
not enough and <br>
> > not "nasty" enough!) <br>
> <br>
> jmeter is an excellent tool for stress/load testing (<br>
> jakarta.apache.org/jmeter/ )<br>
> <br>
> > - New problems could raise, if more or other features from<br>
> > mapserver/mapscript <br>
> > are used then we actualy do. <br>
> > - Memory footprint of the running-tomcat has to be watched!.
What about the<br>
> > size <br>
> > of the application after 100, 500, 600, 800 ...
requests? (I'm not quite<br>
> > shure how to do this!<br>
> <br>
> Use the -Xloggc:/tmp/gc.log to java when starting tomcat and then
run<br>
> the stress tests. You should be able to see that if memory get<br>
> correctly garbage collected the avail mem is almost always equal to
a<br>
> certain initial size.<br>
> Warning: this is not 100% error proof, but it should be start. try
googling...<br>
> <br>
> Ciao,<br>
> Umberto<br>
> <br>
> > Watching Java-Programs is difficult because of garbage-collections
...) <br>
> > <br>
> > Greetings <br>
> > Benedikt <br>
> > <br>
> > Umberto Nicoletti <umberto.nicoletti@gmail.com> schrieb
am 29.06.2005<br>
> > 11:03:46:<br>
> > <br>
> > <br>
> > > On 6/29/05, Benedikt Rothe <umn-ms@hydrotec.de>
wrote:<br>
> > > > <br>
> > > > Dear List <br>
> > > > <br>
> > > > We are using MapScript/Tomcat/Java/OracleSpatial.
<br>
> > > > <br>
> > > > We use mapObj.mapClone() to get a fresh mapObject
<br>
> > > > in each request without reading the Mapfile.
<br>
> > > <br>
> > > Benedikt,<br>
> > > I would not do that (tm). In my apps I recreate a
fresh mapObj with<br>
> > > each request as the overhead is mininum and
the benefits high (so<br>
> > > that the ratio is in favor of this approach).<br>
> > > Besides this is the only known method to work (as
far as I know) and<br>
> > > this stems from the fact that mapserver was in the
beginning (and<br>
> > > still is, with improvements) a CGI. As you might know
cgis are<br>
> > > processes that are created by the web server to serve
a single request<br>
> > > and then exit, so memory cleanup and thread safety
are non-issues for<br>
> > > them.<br>
> > > Even in php mapscript php must be used as a cgi (instead
of a DSO) to<br>
> > > make sure that it works.<br>
> > > <br>
> > > > <br>
> > > > We detected problems after we activated Connection-Pooling:
<br>
> > > > Tomcat crashed in mapObj.delete() <br>
> > > ><br>
> > > <br>
> > > I would not use connection pooling just because it
will not work<br>
> > > reliably with Java Servlets for the reasons explained
above.<br>
> > > <br>
> > > This matter (connection pooling and map cloning) surely
requires<br>
> > > deeper investigation, one of the developers coul step
in to give his<br>
> > > opinion on my statements (which I would sincerely
hope were false, but<br>
> > > fear not). Btw, I seem to recall that the above issues
(long lived<br>
> > > instance against per request instance) were
already discussed on the<br>
> > > list before.<br>
> > > <br>
> > > Best regards,<br>
> > > Umberto<br>
> > > <br>
> > > > Hole thing turned out to be a bug in mapcopy.c
where <br>
> > > > the joins are copied: <br>
> > > > -------------------- <br>
> > > > MS_COPYSTELEM(numjoins); <br>
> > > > <br>
> > > > for (i = 0; i < dst->numprocessing; i++)
{ <br>
> > > > return_value = msCopyJoin(&(dst->joins[i]),
&(src->joins[i])); <br>
> > > > -------------------- <br>
> > > > <br>
> > > > This must be changed to <br>
> > > > -------------------- <br>
> > > > MS_COPYSTELEM(numjoins); <br>
> > > > <br>
> > > > for (i = 0; i < dst->numjoins; i++) { <br>
> > > > return_value = msCopyJoin(&(dst->joins[i]),
&(src->joins[i])); <br>
> > > > -------------------- <br>
> > > > <br>
> > > > There is some other code in mapobject.c, wich
didn't <br>
> > > > raise any problems for us, but from wich I do
think <br>
> > > > that array-allocs are missing. <br>
> > > > I watched the code an *think* these are are not
allocated <br>
> > > > anywhere. I hope, there is no misleading hint:
<br>
> > > > <br>
> > > > ----------------------------<br>
> > > > // I do think, that dst->point is not
allocated.<br>
> > > > // code seems to be unused (?)<br>
> > > > dst->numpoints = src->numpoints;<br>
> > > > for (i = 0; i < dst->numpoints; i++)
{<br>
> > > > MS_COPYPOINT(&(dst->point[i]),
&(src->point[i]));<br>
> > > > }<br>
> > > > ----------------------------<br>
> > > > // I do think, that dst->items and dst->values
is<br>
> > > > // not allocated<br>
> > > > MS_COPYSTELEM(numitems);<br>
> > > > for (i = 0; i < dst->numitems; i++)
{<br>
> > > > MS_COPYSTRING(dst->items[i], src->items[i]);<br>
> > > > MS_COPYSTRING(dst->values[i], src->values[i]);<br>
> > > > }<br>
> > > > <br>
> > > > -----------------------------<br>
> > > > // I'm quite shure, that dst->items
is not allocated<br>
> > > > MS_COPYSTELEM(numitems);<br>
> > > > <br>
> > > > for (i = 0; i < dst->numitems; i++)
{<br>
> > > > MS_COPYSTRING(dst->items[i], src->items[i]);<br>
> > > > }<br>
> > > > <br>
> > > > I hope this is helpful. Greetings <br>
> > > > Benedikt Rothe<br>
> ><br>
</tt></font>