I have created a web application in Apache Cocoon.This website is running properly but after every 3-4 days, it stops responding. It doesn't run until and unless, we restart the tomcat service. In the catalina.2011-05-09.log file, it shows following error:-
"May 9, 2011 3:17:34 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/webresources] is still processing a request that has yet to finish. This is very likely to create a memory leak. You can control the time allowed for requests to finish by using the unloadDelay attribute of the standard Context implementation."
I am not been able to understand the cause of this problem. Can someone suggest me how to resolve this issue?
You are using a library that is starting one or more threads and is not properly shutting them down or releasing other resources captured by the thread. This often happens with things like Apache HTTP components (I get this error with Http Components) and anything that uses separate threads internally. What libraries are you using in your Cocoon application?
It is telling you the issue:
[...] is still processing a request that has yet to finish
You need to find out what that request is/is going to. One easy way is to have something like PsiProbe installed.
Also, it's not a bad idea to restart Tomcat every night. It can help alleviate these kinds of issues until you find the root cause.
Related
with a new project we encountered some strange behaviour on our ColdFusion application.
Whenever a single request is initiated from the browser, the code of the cfml-templates is
executed multiple times. Upon viewing the corresponding log-files we found out, that indeed
for some reason the same request fires the evaluation in our application multiple times. One request
generates several entries. This is especially the case for long-running requests, such as database imports.
The ColdFusion application implements a REST-service, but even on manually requesting a resource,
such as a certain cfml page, on the same application - the code gets executed an unknown amount of times(variable initializations, database write-operations etc. take place), and if the request runs too long (cap at around ~4-6 seconds) there is no response to the browser.
About the infrastructure:
The application is Coldfusion18 with Tomcat Standard Edition
The webserver is an Apache (2.4.6).
Everything runs on a Linux machine with Cent OS 7.7
The corresponding Java version is 11.0.4
Our best guess is that there might be some misscommunication between the coldfusion connector with
the apache webserver. We actually searched for some configuration parameters that could cause the
problem, without success. Upon an installation on a windows machine we did not encounter that error.
Anyone got any idea?
we just found our answer in the following post:
Link to Solution
Our web app process is restarting regularly and we are unable to determine the reason.
When looking into Application Events (using the 'Diagnostics and solve problems' blade in the Azure Portal), there exists a bunch of the following Info logs by 'IIS AspNetCore Module'
Event ID 1005:
Failed to gracefully shutdown process '14040'.
Event ID 1001:
Application 'MACHINE/WEBROOT/APPHOST/myapplication__xxxx' started process '31628' successfully and is listening on port '17663'.
There is nothing fishy with general resource usage and nothing in our application logs.
What is the best way to troubleshoot the reason behind these process restarts?
EDIT 1:
After fiddling around with web logging in the Web App's Diagnostic Logs, I now get an error logged from W3SVC-WP after each restart, but the message is nonsense:
1<br/>5<br/>50000780
EDIT 2:
Event Id 2284 refers to this:
FailedRequestTracing module failed to write buffered events to log
file for the request that matched failure definition. No logs will be
generated until this condition is corrected. The problem happened at
least %1 times in the last %2 minutes. The data is the error.
I'm not sure if this could be related to our Diagnostic Logs configuration, but seems unlikely.
EDIT 3:
As per Brando Zhang's suggestion, I've used the Web App Crash Diagnoser extension and tried monitoring 2nd Chance Unhandled Exceptions on both my application process AND on w3wp, but nothing is dumped.
From how I understand it, 1st Chance Exceptions will not crash the process, so no need to monitor these.
Very likely application is crashing due to fatal exception and causing the restarts.
On Azure App Service platform.You can use the Diagnostics as a
Service (DaaS) to troubleshoot this
It can also do an analysis and tell you the root cause most of the time.More step by step infofrmation can be found on this msdn blog .Also refer tips for using crash diagnoser
I have a Perl web app served by Apache httpd using plain mod_cgi or optionally mod_perl with PerlHandler ModPerl::Registry. Recently the app encountered the error Script timed out before returning headers on some invocations and behaved differently afterwards: While some requests seemed to be processed successfully in the background, after httpd sent status 504 to the client, others didn't.
So how exactly behaves httpd AFTER it reached its configured timeout and sent the error to the client? The request/response cycle is finished now, so I guess things like KeepAlive come into play to decide if the TCP connections stays alive or not etc. But what happens to the running script in which environment, e.g. mod_cgi vs. mod_perl?
Especially in mod_cgi, where new processes are started for each request, I would have guessed that httpd keeps the processes simply running. Because all our Perl files have a shebang, I'm not even sure if httpd is able to track the processes and does so or not. That could be completely different with mod_perl, because in that case httpd is aware of the interpreters and what they are doing etc. In fact, the same operation which timed out using plain mod_cgi, succeeded using mod_perl without any timeout, but even with a timeout in mod_cgi at least one request succeeded afterwards as well.
I find this question interesting for other runtimes than Perl as well, because they share the concepts of plain mod_cgi vs. some persistent runtime embedded into the httpd processes or using some external daemons.
So, my question is NOT about how to get the error message away. Instead I want to understand how httpd behaves AFTER the error occurred, because I don't seem to find much information on that topic. It's all just about increasing configuration values and try to avoid the problem in the first place, which is fine, but not what I need to know currently.
Thanks!
Both mod_cgi and mod_cgid set a cleanup function on the request scope to kill the child process, but they do it slightly different ways. This would happen shortly after the timeout is reported (a little time for mod_cgi to return control, the error response to be written, the request logged, etc)
mod_cgi uses a core facility in httpd that does SIGTERM, sleeps for 3 seconds, then does a SIGKILL.
I am backing a web app with a Flask API that returns custom error codes. The API runs through Apache and the WSGI module, in daemon mode.
I included a WSGIErrorOverride Off instruction in the Apache conf file for the API (which is supposed to be the default but I included it anyway).
Yet anytime my Flask app returns a custom error code (they work when I run the app using the built-in server), Apache sends an error 500. How can I prevent that?
Thanks to comments by duskwuff and Graham Dumpleton, I found that the problem doesn't come from Apache WSGI but from my Flask app.
More precisely, I was using the Flask-RESTful package, which is in charge, among other things, of transforming my views' return values into actual responses.
When those views are decorated (here with an equivalent of #login_required), those decorators are called by the Flask-RESTful package itself, and when an exception is thrown, something goes wrong.
For some reason, my app returns the custom error when I run the built-in server and an error 500 when I run it over Apache. Not quite sure why yet, I'm guessing Flask-RESTful is doing something that is not WSGI-compliant. I was on the verge of dropping it anyway for other reasons, so I'm OK with this solution.
Update: it looks like the problem does indeed come from Flask-RESTful: https://github.com/flask-restful/flask-restful/issues/372
I'm about a month away developing my silverlight application (this is my first). Everything went rather smoothly until today, when out of the blue I started getting this message:
An error occurred while trying to make a request to URI 'http://localhost:2682/Services/Authentication/LoginService.svc'. This could be due to attempting to access a service in a cross-domain way without a proper cross-domain policy in place, or a policy that is unsuitable for SOAP services. You may need to contact the owner of the service to publish a cross-domain policy file and to ensure it allows SOAP-related HTTP headers to be sent. This error may also be caused by using internal types in the web service proxy without using the InternalsVisibleToAttribute attribute. Please see the inner exception for more details.
I'm using WCF Services and this issue never appeared until now.
I've added a clientdomain.xml and clientaccesspolicy.xml file to my [projectname].web folder, and re-wrote them about a 1000 different ways.
I've also used Fiddler and it shows me that the error is on both those files, the error is
[Fiddler] The socket connection to localhost failed. ErrorCode: 10061. No connection could be made because the target machine actively refused it 127.0.0.1:2682
I've searched the error "10061" and it has to do with socket definition. But I couldn't find any solution to that.
Don't know if it has anything to do with it, but my "ASP.net Development Server" port is 6939.
Keep in mind that the app has NOT been deployed, so this is only happening locally. I'm using MS VS 2010 and MS SQL Server 2008.
Am I doing anything wrong or is this a silverlight issue??
On a last note, I haven't changed anything on Port, socket or service configuration. Last thing I was doing was editing a XAML file on client side and and the app started throwing me this error.
Need help, can't do anything until this is solved!!!!
Thanks.
i think you are using you app on localhost and a dynamic port is getting assigned and this port is not fixed and every run and that causes the refuse problem. if you want to fix this, create a solid url for example,
http://localhost/apps/Services/Authentication/LoginService.svc
Well, last night, just before I went to bed, I noticed something odd. In my "ServiceReferences.ClientConfig" file, the endpoint ports for each one of my services where diferent from the ones the silverlight machine used, so going on a hunch (and because I was reaching my sanity breakpoint) I decided to eliminate all my Service References and re-add them again.
I worked... go figure. Still don't know why this happened and if anyone could shed some light on the subject, I would appreciate it. It's kinda of annoying having to re-add all my services references. Right now I have only 6 of them, but in the near future they may go over 20, and if this happens again... well, it's going to be a real pain...
Thanks