Due to the current gap in continued funding from the U.S. National Science Foundation (NSF), the NSF Unidata Program Center has temporarily paused most operations. See NSF Unidata Pause in Most Operations for details.
Due to the current gap in continued funding from the U.S. National Science Foundation (NSF), the NSF Unidata Program Center has temporarily paused most operations. See NSF Unidata Pause in Most Operations for details.
Hi Heiko, That is great. Thanks. I'm a bit swamped through next week but I will jump on this the following week before I get to some other WMS work. Thanks, Ethan On 3/5/2010 4:44 AM, Heiko Klein wrote: > Hi, > > finally, I managed to generate a simple case how to reproduce this error: > > a) start tomcat > b) abort fetching some maps (3-4 times on a tomcat with > 10thredds/HTTP1.1 connector), i.e. call > GET > 'http://localhost:8081/thredds/wms/data/met.no/hirlam12/wam_nsea.fc.20090604.nc?REQUEST=GetMap&LAYERS=significant_wave_height&PALETTE=redblue&SERVICE=WMS&FORMAT=image/png&VERSION=1.3.0&CRS=EPSG:4326&BBOX=-30,-60,30,90&WIDTH=400&HEIGHT=400&STYLES=BOXFILL/ncview' >> /dev/null > and abort this call before it is finished. (Ctrl-C) > c) get some 'getCapabilities' documents: > while [ 1 ]; do GET > 'http://localhost:8081/thredds/wms/data/met.no/hirlam12/wam_nsea.fc.20090604.nc?service=WMS&version=1.3.0&request=GetCapabilities' >> testCap.xml; ls -l testCap.xml; done > ... > -rw-r--r-- 1 heikok heikok 172126 2010-03-05 12:11 testCap.xml > -rw-r--r-- 1 heikok heikok 172126 2010-03-05 12:11 testCap.xml > -rw-r--r-- 1 heikok heikok 172126 2010-03-05 12:11 testCap.xml > -rw-r--r-- 1 heikok heikok 0 2010-03-05 12:11 testCap.xml > -rw-r--r-- 1 heikok heikok 172126 2010-03-05 12:11 testCap.xml > -rw-r--r-- 1 heikok heikok 172126 2010-03-05 12:11 testCap.xml > > > When the capabilites document with 0 byte size is fetched, the earlier > mentioned exception is thrown. > > > Since step b) is the crucial step to reproduce the 0 byte document, I > guess there is somewhere a badly caught ClientAbortException/IOException > when writing to the responses OutputStream, leaving a tomcat-thread in > an invalid state. > > > We can solve this problem currently by adding a proxy in front of > thredds (apache mod_proxy) which seems to swallow all > client-connection-aborts before they reach tomcat. > > Best regards, > > Heiko > > On 2010-02-19 16:54, Heiko Klein wrote: >> Hi, >> >> I'm still trying to track down this problem, so here a short update: >> >> The ncWMS/TDS crashes seems to be connected to concurrency: The problem >> occurs when reloading the wms-client (openlayers in firefox), that means >> GetCapabilites and GetMap are run in parallel. We're downloading tiles, >> so reloading will fetch one capability doc + approx 12 maps. >> >> * If I configure tomcat to only use one thread, and use the default >> 'HTTP/1.1' connector, the problem disappears (but response-times are >> very slow). >> * Using 4 threads + 'HTTP/1.1', the problem appears very fast. (one or >> two reloads) >> * Using the 'Nio' connector and 4 threads, the problem appears, but not >> so fast (3-4 reloads) >> * Using the 'Nio' connector with only one thread, is about the same as >> Nio with several threads. >> >> >> Best regards, >> >> Heiko >> >> _______________________________________________ >> thredds mailing list >> thredds@xxxxxxxxxxxxxxxx >> For list information or to unsubscribe, visit: >> http://www.unidata.ucar.edu/mailing_lists/ >
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