Tamas Szekeres wrote: > > You can probably control the caching effect by setting LABELCACHE OFF for > all of layers. However I'm a bit hesitant to think that this is due to a > missing lock around the labelcache itself since it doesn't contain static > variables. >
I think you might be right, and that this crash might be another red herring. What I'm doing here is stressing the limits of the system to see what it can handle. There's various interactions between mapserver, the JVM, tomcat, and postgres, and when things go badly, it's not entirely clear what's the cause and what's the effect. I tried a few related tests: 1) I commented out all LAYER's that had any LABEL declarations. In this instance, tomcat indeed did NOT crash. However, under stress there were problems reported by tomcat and by postgres, but that's (sort of) okay. 2) I kept all of the LAYER's, but for those with LABEL declarations I set LABELCACHE OFF. The previous crash at mapfile.c:msFreeLabelCacheSlot() did NOT occur. However, intead, there was a new crash: (msClipPolygonRect) mapprimitive.c:605 (msDrawShape) mapdraw.c:1609 (msDrawVectorLayer) mapdraw.c:887 (msDrawLayer) mapdraw.c:718 (msDrawMap) mapdraw.c:432 (mapObj_draw) mapscript/java/mapscript_wrap.c:1714 (Java_edu_umn_gis_mapscript_mapscriptJNI_mapObj_1draw) mapscript/java/mapscript_wrap.c:20612 But again this coincided with other things going badly under stress, so I'm not really sure if mapserver is to blame. Ideally, tomcat and the JVM should never crash. If things go badly, the system should become less responsive, and possibly refuse additional requests, or cancel existing ones. Crashing is clearly a wrong thing to do with respect to correctness. But given the nature of what I'm seeing, it's not clear to me that mapserver is the piece at fault. I've spent some time trying to tune tomcat and postgres and some OS parameters a bit. While I'm still having a few issues, some of which might (or might not) be genuine mapserver issues, now that the system is tuned better, I'm not seeing any more JVM crashes, even under heavy load. (Although it might just be that the definition of "heavy" has shifted higher, and I'm no longer stressing things that much relative to that.) Anyway, I will deal with the issues that I am having in separate mailing list threads. But for the time being I think that maybe my original concern here is a non-issue. I'll reply back with more details if I see any more observations that cause me to think differently. - Rich -- View this message in context: http://www.nabble.com/missing-lock-in-mapfile.c%3AmsFreeLabelCacheSlot%28%29---tp15699786p15748847.html Sent from the Mapserver - User mailing list archive at Nabble.com. _______________________________________________ mapserver-users mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/mapserver-users
