Re: Can two Tomcat web apps deadlock each other?
Alexey, Thanks for taking the time to reply. I'll try all your suggestions but I wanted to investigate the windows vs linux possibilities. Does the fact that this Tomcat behavior does not occur on the windows-based development server offer any clue as to what may be happening on the linux server when Tomcat hangs? Thanks again, -=bill Alexey Solofnenko wrote: There can be a simple problem with locking - see http://tomcat.apache.org/faq/windows.html#lock . On Linux the files are usually not locked, so you can get class not found exception when a jar file is replaced with a new one. Ask administrators to get the stack trace (and check if CPU is at 100% or not - maybe it is not a deadlock). Otherwise you can look for a problem for a very long time. You can also add try/catch with finite number of retries around connection code. Please also check that your application shuts down cleanly - no exceptions are thrown during shutdown (but they should be logged) and preferably there are no finally() methods. Wm.A.Stafford wrote: Thanks Alexey. Unfortunately, the server in question is not ours and we do not even have log in on it, so any kind of sane analysis is probably out of the question. All we can do is try deploying another version with changes that will either fix the problem (we hope) or yield some more information about what is going on. -=bill Alexey Solofnenko wrote: Everything is possible, but unlikely. Please try running server stack trace from http://tmitevski.users.mcs2.netarray.com/stacktrace/app/launch.jnlp to get a thread dump. It will show the list of threads and what locks they have acquired and what locks they are waiting for. - Alexey. Wm.A.Stafford wrote: We are deploying a newer version of a web app to run in the same Tomcat instance (1.4.31) as the existing version. On our development servers, winXP, if the new version encounters a startup problem the production app will start and only the new version will fail. On the production server, which is linux, Tomcat seems to 'hang' on the first failure encountered when starting the new app and nothing further happens. Tomcat has to be restarted after deleting the new app when it enters this state. In the localhost log the last log entry is the exception logged from the new app and there is no further logging. Since we have been doing some database changes the usual error that causes this is Jakarta DBCP connection failure but we have also seen it for a missing class file. So I don't think the error per se is at the root of the problem. To me this looks like a deadlock. Is it possible for one Tomcat web application to deadlock with another? An obvious difference is windows vs linux servers. Could there be some config issue for Tomcat on linux that would lead to this behavior? We are completely stumped by this, any ideas or suggestions would be appreciated. -=bill - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: Can two Tomcat web apps deadlock each other?
From: Wm.A.Stafford [mailto:[EMAIL PROTECTED] Does the fact that this Tomcat behavior does not occur on the windows-based development server offer any clue as to what may be happening on the linux server when Tomcat hangs? I'm going to take a guess: server load. How heavily do you stress-test your webapp on the development server? What with? How many concurrent requests? - Peter - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Can two Tomcat web apps deadlock each other?
Peter, Thanks for replying. I don't think server load is a factor but I will look into it. What makes me think that load is probably not the cause is that when there are no startup errors everything starts and runs as normal in the normal amount of time. The problem occurs when one app fails during startup. For unknown reasons Tomcat either does not get notified of the failure and is left some sort of waiting state or Tomcat gets hung trying to shutdown the failed app. Thanks again for replying, -=beeky Peter Crowther wrote: From: Wm.A.Stafford [mailto:[EMAIL PROTECTED] Does the fact that this Tomcat behavior does not occur on the windows-based development server offer any clue as to what may be happening on the linux server when Tomcat hangs? I'm going to take a guess: server load. How heavily do you stress-test your webapp on the development server? What with? How many concurrent requests? - Peter - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Can two Tomcat web apps deadlock each other?
Everything is possible, but unlikely. Please try running server stack trace from http://tmitevski.users.mcs2.netarray.com/stacktrace/app/launch.jnlp to get a thread dump. It will show the list of threads and what locks they have acquired and what locks they are waiting for. - Alexey. Wm.A.Stafford wrote: We are deploying a newer version of a web app to run in the same Tomcat instance (1.4.31) as the existing version. On our development servers, winXP, if the new version encounters a startup problem the production app will start and only the new version will fail. On the production server, which is linux, Tomcat seems to 'hang' on the first failure encountered when starting the new app and nothing further happens. Tomcat has to be restarted after deleting the new app when it enters this state. In the localhost log the last log entry is the exception logged from the new app and there is no further logging. Since we have been doing some database changes the usual error that causes this is Jakarta DBCP connection failure but we have also seen it for a missing class file. So I don't think the error per se is at the root of the problem. To me this looks like a deadlock. Is it possible for one Tomcat web application to deadlock with another? An obvious difference is windows vs linux servers. Could there be some config issue for Tomcat on linux that would lead to this behavior? We are completely stumped by this, any ideas or suggestions would be appreciated. -=bill - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] -- Alexey N. Solofnenko http://trelony.cjb.net/ Pleasant Hill, CA (GMT-8 usually) smime.p7s Description: S/MIME Cryptographic Signature
Re: Can two Tomcat web apps deadlock each other?
Thanks Alexey. Unfortunately, the server in question is not ours and we do not even have log in on it, so any kind of sane analysis is probably out of the question. All we can do is try deploying another version with changes that will either fix the problem (we hope) or yield some more information about what is going on. -=bill Alexey Solofnenko wrote: Everything is possible, but unlikely. Please try running server stack trace from http://tmitevski.users.mcs2.netarray.com/stacktrace/app/launch.jnlp to get a thread dump. It will show the list of threads and what locks they have acquired and what locks they are waiting for. - Alexey. Wm.A.Stafford wrote: We are deploying a newer version of a web app to run in the same Tomcat instance (1.4.31) as the existing version. On our development servers, winXP, if the new version encounters a startup problem the production app will start and only the new version will fail. On the production server, which is linux, Tomcat seems to 'hang' on the first failure encountered when starting the new app and nothing further happens. Tomcat has to be restarted after deleting the new app when it enters this state. In the localhost log the last log entry is the exception logged from the new app and there is no further logging. Since we have been doing some database changes the usual error that causes this is Jakarta DBCP connection failure but we have also seen it for a missing class file. So I don't think the error per se is at the root of the problem. To me this looks like a deadlock. Is it possible for one Tomcat web application to deadlock with another? An obvious difference is windows vs linux servers. Could there be some config issue for Tomcat on linux that would lead to this behavior? We are completely stumped by this, any ideas or suggestions would be appreciated. -=bill - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Can two Tomcat web apps deadlock each other?
There can be a simple problem with locking - see http://tomcat.apache.org/faq/windows.html#lock . On Linux the files are usually not locked, so you can get class not found exception when a jar file is replaced with a new one. Ask administrators to get the stack trace (and check if CPU is at 100% or not - maybe it is not a deadlock). Otherwise you can look for a problem for a very long time. You can also add try/catch with finite number of retries around connection code. Please also check that your application shuts down cleanly - no exceptions are thrown during shutdown (but they should be logged) and preferably there are no finally() methods. Wm.A.Stafford wrote: Thanks Alexey. Unfortunately, the server in question is not ours and we do not even have log in on it, so any kind of sane analysis is probably out of the question. All we can do is try deploying another version with changes that will either fix the problem (we hope) or yield some more information about what is going on. -=bill Alexey Solofnenko wrote: Everything is possible, but unlikely. Please try running server stack trace from http://tmitevski.users.mcs2.netarray.com/stacktrace/app/launch.jnlp to get a thread dump. It will show the list of threads and what locks they have acquired and what locks they are waiting for. - Alexey. Wm.A.Stafford wrote: We are deploying a newer version of a web app to run in the same Tomcat instance (1.4.31) as the existing version. On our development servers, winXP, if the new version encounters a startup problem the production app will start and only the new version will fail. On the production server, which is linux, Tomcat seems to 'hang' on the first failure encountered when starting the new app and nothing further happens. Tomcat has to be restarted after deleting the new app when it enters this state. In the localhost log the last log entry is the exception logged from the new app and there is no further logging. Since we have been doing some database changes the usual error that causes this is Jakarta DBCP connection failure but we have also seen it for a missing class file. So I don't think the error per se is at the root of the problem. To me this looks like a deadlock. Is it possible for one Tomcat web application to deadlock with another? An obvious difference is windows vs linux servers. Could there be some config issue for Tomcat on linux that would lead to this behavior? We are completely stumped by this, any ideas or suggestions would be appreciated. -=bill - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] -- Alexey N. Solofnenko http://trelony.cjb.net/ Pleasant Hill, CA (GMT-8 usually) smime.p7s Description: S/MIME Cryptographic Signature
