Production Reliability

[Jing Zhou <ji...@hotmail.com>]

  I once explained to our ISP according my understanding that using the 
Tomcat as an out-of-process will not crash the web server. I have done a lot 
of experiments in our lab and everything is fine for Tomcat. Then yestoday I 
helped our ISP (who is using IIS 4.0 on NT server 4 (SP6)) to install Tomcat 
3.1 with IIS 4.0. Within an hour, we got "HANDLER THREAD PROBLEM: 
java.lang.NullPointerException." when I testing the jsp examples.

  The real problem is that when such null pointer exception thrown, the 
whole IIS web server is broken down which is serving many sites for other 
companies. We repeated the process several times yestoday on the ISP 
production web server and the only solution is to shutdown the Tomcat NT 
service (the redirector dll are kept) and then IIS can be brought up.

  Then I researched the history the null pointer exception in this email 
archive, and found that some people are concerned about it too. But I have 
no clue on what is the current status for this bug. Will be it fixed in the 
Tomcat 3.2? or already fixed in Tomcat 3.2 b2? Could someone give me some 
information about this?

  The next thing I am thinking is the possibility of the way to shield the 
IIS from the internal crash of Tomcat. In other words, no matter what 
happens to the out-of-process Tomcat (e.g. null pointer exception, which 
will be thrown again and again when new codes come in with high posibility), 
IIS should not be and must not be broken down. Is this possible? The 
isapi.log file is shown as follows when I am guessing number 47 and then the 
null pointer exception thrown and crashed the IIS server:

[jk_isapi_plugin.c (385)]: In HttpFilterProc test redirection of 
/examples/jsp/num/numguess.jsp
[jk_uri_worker_map.c (286)]: Into jk_uri_worker_map_t::map_uri_to_worker
[jk_uri_worker_map.c (338)]: jk_uri_worker_map_t::uri_worker_map_open, done 
with ajp12
[jk_isapi_plugin.c (395)]: In HttpFilterProc 
/examples/jsp/num/numguess.jsp?guess=47 should redirect to ajp12
[jk_worker.c (139)]: Into wc_get_worker_for_name ajp12
[jk_worker.c (143)]: wc_get_worker_for_name, done  found a worker
[jk_ajp12_worker.c (223)]: Into jk_worker_t::get_endpoint
[jk_ajp12_worker.c (121)]: Into jk_endpoint_t::service
[jk_connect.c (107)]: Into jk_open_socket
[jk_connect.c (114)]: jk_open_socket, try to connect socket = 8372
[jk_connect.c (123)]: jk_open_socket, after connect ret = -1
[jk_connect.c (142)]: jk_open_socket, connect() failed errno = 61
[jk_ajp12_worker.c (134)]: In jk_endpoint_t::service, sd = -1
[jk_ajp12_worker.c (152)]: In jk_endpoint_t::service, Error sd = -1
[jk_ajp12_worker.c (163)]: Into jk_endpoint_t::done
[jk_isapi_plugin.c (385)]: In HttpFilterProc test redirection of /
[jk_uri_worker_map.c (286)]: Into jk_uri_worker_map_t::map_uri_to_worker
[jk_uri_worker_map.c (346)]: jk_uri_worker_map_t::uri_worker_map_open, done 
with NULL
[jk_isapi_plugin.c (385)]: In HttpFilterProc test redirection of 
/images/guide.gif
[jk_uri_worker_map.c (286)]: Into jk_uri_worker_map_t::map_uri_to_worker
[jk_uri_worker_map.c (346)]: jk_uri_worker_map_t::uri_worker_map_open, done 
with NULL
[jk_isapi_plugin.c (385)]: In HttpFilterProc test redirection of 
/images/applet.gif
[jk_uri_worker_map.c (286)]: Into jk_uri_worker_map_t::map_uri_to_worker
[jk_uri_worker_map.c (346)]: jk_uri_worker_map_t::uri_worker_map_open, done 
with NULL
[jk_uri_worker_map.c (127)]: Into jk_uri_worker_map_t::uri_worker_map_free
[jk_uri_worker_map.c (273)]: Into jk_uri_worker_map_t::uri_worker_map_close
[jk_uri_worker_map.c (278)]: jk_uri_worker_map_t::uri_worker_map_close, NULL 
parameter
[jk_uri_worker_map.c (134)]: In jk_uri_worker_map_t::uri_worker_map_free, 
NULL parameters
[jk_worker.c (125)]: Into wc_close
[jk_worker.c (127)]: wc_close, done

I composed a Tomcat Support Page at http://netspread.com/tomcat.html.
In the document, you will find detail configurations on the ISP server. The 
page can help new comers to Tomcat like myself and our ISP. If our 
configurations are not correct or inappropriate at some point, please let me 
know.

Anyway, I am facing presure from our ISP, we need some answers before we can 
restart the Tomcat on the production server.

Thanks,
Jing

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