RE: Plz help! Tomcat blocks when calling itself - i am desperate!
Do really need to use SingleThreadedModel for your servlets? In general its best avoid this if at all possible. Section 3.2 of the specification only requires that a servlet container must guarantee that only one thread is executing through a specific servlet instance an any time. Containers *can* create multiple instances to handle multiple simultaneous requests, but they aren't *required* to do this. Thus this can cause portabilty problems across various containers. I'll take a look at the SingleThreadedModel code in Tomcat 3.2.2 and see fi anything jumps out at me. Your example code will help a lot. Thanks. -Original Message- From: Bari, Naeem [mailto:[EMAIL PROTECTED]] Sent: Monday, June 25, 2001 4:51 PM To: 'Marc Saegesser'; [EMAIL PROTECTED] Subject: RE: Plz help! Tomcat blocks when calling itself - i am desperate! Marc, Thanks for your response. I will put together a little servlet that demonstrates this. I did find out the *cause* of the problem. I think this is a bug in tomcat... The situation is this: If you have a servlet that implements the SingleThreadedModel AND this servlet opens a URL back to a servlet in the same container THEN tomcat will block/deadlock This did not happen with JServ or any other servlet container. I commented out the impements sigleThreadedModel line and it worked like a charm. Hope this helps in determining the problem. I will send the servlet to you by tomorrow. Thanks, naeem -Original Message- From: Marc Saegesser [mailto:[EMAIL PROTECTED]] Sent: Monday, June 25, 2001 4:24 PM To: [EMAIL PROTECTED] Cc: [EMAIL PROTECTED] Subject: RE: Plz help! Tomcat blocks when calling itself - i am desperate! Any chance you could send a small sample application that demonstrates the problem? -Original Message- From: Bari, Naeem [mailto:[EMAIL PROTECTED]] Sent: Monday, June 25, 2001 2:23 PM To: '[EMAIL PROTECTED]' Subject: Plz help! Tomcat blocks when calling itself - i am desperate! I apologize for posting in the dev group, but postings to the user group have not shed any light on my problem, and I getting desperate! Here is my problem: -- My environment: Solaris 8 (fully patched) jdk 1.3.1, with hotspot enabled tomcat 3.2.2 apache 1.3.19 The problem: I have a servlet that opens a URL connection to the servlet container. So if I call http://blah/blinky, where blinky is my servlet, it is possible under some situations for this servlet to open a URL such as http://blah/lumpy, where lumpy is some other servlet. This is part of a largish site publishing framework I built on top of JServ. Now, things worked great with JServ, but I am having a devil of a time getting this to work in Tomcat. Observations: When the blinky servlet opens a URL to the same tomcat instance, the log entries for mod_jk go as far as making the call to marshal stuff before calling tomcat - as seen by the mod_jk.log entry: [jk_ajp13.c (480)]: ajp13_marshal_into_msgb - Done At this point, nothing happens. I *should* be seeing entries for the jk_open_socket function, but they never appear. What I have tried: - I have disabled the default 8080 listener, thinking it may be interfering. No luck - I changed the cachesize of the ajp12 and ajp13 workers to 8 from the default of 1. No luck - I added the min_spare_threads parameter to the entries for the ajp12 and ajp13 connectors in server.xml No luck - switched between tomcat 3.2.1 and 3.2.2 *and* 4.0b5 No luck - upgraded apache to 1.3.19 No luck - switched between jdk1.2.2 and jdk1.3.1 No Luck - switched between solaris and win2k No luck - Torn my hair out from the roots No luck I am at my wits end. Any help will be gratefully accepted. TIA, naeem
RE: Plz help! Tomcat blocks when calling itself - i am desperate!
Any chance you could send a small sample application that demonstrates the problem? -Original Message- From: Bari, Naeem [mailto:[EMAIL PROTECTED]] Sent: Monday, June 25, 2001 2:23 PM To: '[EMAIL PROTECTED]' Subject: Plz help! Tomcat blocks when calling itself - i am desperate! I apologize for posting in the dev group, but postings to the user group have not shed any light on my problem, and I getting desperate! Here is my problem: -- My environment: Solaris 8 (fully patched) jdk 1.3.1, with hotspot enabled tomcat 3.2.2 apache 1.3.19 The problem: I have a servlet that opens a URL connection to the servlet container. So if I call http://blah/blinky, where blinky is my servlet, it is possible under some situations for this servlet to open a URL such as http://blah/lumpy, where lumpy is some other servlet. This is part of a largish site publishing framework I built on top of JServ. Now, things worked great with JServ, but I am having a devil of a time getting this to work in Tomcat. Observations: When the blinky servlet opens a URL to the same tomcat instance, the log entries for mod_jk go as far as making the call to marshal stuff before calling tomcat - as seen by the mod_jk.log entry: [jk_ajp13.c (480)]: ajp13_marshal_into_msgb - Done At this point, nothing happens. I *should* be seeing entries for the jk_open_socket function, but they never appear. What I have tried: - I have disabled the default 8080 listener, thinking it may be interfering. No luck - I changed the cachesize of the ajp12 and ajp13 workers to 8 from the default of 1. No luck - I added the min_spare_threads parameter to the entries for the ajp12 and ajp13 connectors in server.xml No luck - switched between tomcat 3.2.1 and 3.2.2 *and* 4.0b5 No luck - upgraded apache to 1.3.19 No luck - switched between jdk1.2.2 and jdk1.3.1 No Luck - switched between solaris and win2k No luck - Torn my hair out from the roots No luck I am at my wits end. Any help will be gratefully accepted. TIA, naeem
RE: Plz help! Tomcat blocks when calling itself - i am desperate!
Marc, Thanks for your response. I will put together a little servlet that demonstrates this. I did find out the *cause* of the problem. I think this is a bug in tomcat... The situation is this: If you have a servlet that implements the SingleThreadedModel AND this servlet opens a URL back to a servlet in the same container THEN tomcat will block/deadlock This did not happen with JServ or any other servlet container. I commented out the impements sigleThreadedModel line and it worked like a charm. Hope this helps in determining the problem. I will send the servlet to you by tomorrow. Thanks, naeem -Original Message- From: Marc Saegesser [mailto:[EMAIL PROTECTED]] Sent: Monday, June 25, 2001 4:24 PM To: [EMAIL PROTECTED] Cc: [EMAIL PROTECTED] Subject: RE: Plz help! Tomcat blocks when calling itself - i am desperate! Any chance you could send a small sample application that demonstrates the problem? -Original Message- From: Bari, Naeem [mailto:[EMAIL PROTECTED]] Sent: Monday, June 25, 2001 2:23 PM To: '[EMAIL PROTECTED]' Subject: Plz help! Tomcat blocks when calling itself - i am desperate! I apologize for posting in the dev group, but postings to the user group have not shed any light on my problem, and I getting desperate! Here is my problem: -- My environment: Solaris 8 (fully patched) jdk 1.3.1, with hotspot enabled tomcat 3.2.2 apache 1.3.19 The problem: I have a servlet that opens a URL connection to the servlet container. So if I call http://blah/blinky, where blinky is my servlet, it is possible under some situations for this servlet to open a URL such as http://blah/lumpy, where lumpy is some other servlet. This is part of a largish site publishing framework I built on top of JServ. Now, things worked great with JServ, but I am having a devil of a time getting this to work in Tomcat. Observations: When the blinky servlet opens a URL to the same tomcat instance, the log entries for mod_jk go as far as making the call to marshal stuff before calling tomcat - as seen by the mod_jk.log entry: [jk_ajp13.c (480)]: ajp13_marshal_into_msgb - Done At this point, nothing happens. I *should* be seeing entries for the jk_open_socket function, but they never appear. What I have tried: - I have disabled the default 8080 listener, thinking it may be interfering. No luck - I changed the cachesize of the ajp12 and ajp13 workers to 8 from the default of 1. No luck - I added the min_spare_threads parameter to the entries for the ajp12 and ajp13 connectors in server.xml No luck - switched between tomcat 3.2.1 and 3.2.2 *and* 4.0b5 No luck - upgraded apache to 1.3.19 No luck - switched between jdk1.2.2 and jdk1.3.1 No Luck - switched between solaris and win2k No luck - Torn my hair out from the roots No luck I am at my wits end. Any help will be gratefully accepted. TIA, naeem
