Tomcat 6.0.32 ClientAbortException java.io.IOException

Discussion:

Alec Swan

2011-08-04 16:26:40 UTC

Hello,

We are experiencing a problem on our production servers causing our
HTTP clients to hang. I apologize for cross-posting with Metro forum
but this is a critical problem for us.

It looks like client SOAP HTTP requests get dropped/terminated by
Tomcat or metro without notifying the client that request was
terminated leaving the client waiting indefinitely for response.

Here is what we observed:
1. Client makes a SOAP call to the server
2. Tomcat receives HTTP request and we can see it listed on Tomcat Manager page
3. After about 5 minutes HTTP request disappears from the list of
active HTTP request
4. The client is still waiting for response

We also noticed the following exception logged in catalina.out. It is
thrown around the same time when the problem above occurs but we are
not sure if there is a direct correlation between them.

Aug 1, 2011 12:07:44 AM
com.sun.xml.ws.transport.http.servlet.WSServletDelegate doGet

SEVERE: caught throwable

javax.xml.ws.WebServiceException: com.ctc.wstx.exc.WstxIOException: null

at com.sun.xml.ws.encoding.StreamSOAPCodec.encode(StreamSOAPCodec.java:112)

at com.sun.xml.ws.encoding.SOAPBindingCodec.encode(SOAPBindingCodec.java:278)

at com.sun.xml.ws.transport.http.HttpAdapter.encodePacket(HttpAdapter.java:383)

at com.sun.xml.ws.transport.http.HttpAdapter.access$100(HttpAdapter.java:93)

at com.sun.xml.ws.transport.http.HttpAdapter$HttpToolkit.handle(HttpAdapter.java:529)

at com.sun.xml.ws.transport.http.HttpAdapter.handle(HttpAdapter.java:288)

at com.sun.xml.ws.transport.http.servlet.ServletAdapter.handle(ServletAdapter.java:143)

at com.sun.xml.ws.transport.http.servlet.WSServletDelegate.doGet(WSServletDelegate.java:155)

at com.sun.xml.ws.transport.http.servlet.WSServletDelegate.doPost(WSServletDelegate.java:189)

at com.sun.xml.ws.transport.http.servlet.WSServlet.doPost(WSServlet.java:76)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)

at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:470)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)

at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:864)

at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)

at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1665)

at java.lang.Thread.run(Unknown Source)

Caused by: com.ctc.wstx.exc.WstxIOException: null

at com.ctc.wstx.sw.BaseStreamWriter.finishDocument(BaseStreamWriter.java:1687)

at com.ctc.wstx.sw.BaseStreamWriter.writeEndDocument(BaseStreamWriter.java:585)

at com.sun.xml.ws.message.saaj.SAAJMessage.writeTo(SAAJMessage.java:368)

at com.sun.xml.ws.encoding.StreamSOAPCodec.encode(StreamSOAPCodec.java:109)

... 24 more

Caused by: ClientAbortException: java.io.IOException

at org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:319)

at org.apache.catalina.connector.OutputBuffer.flush(OutputBuffer.java:288)

at org.apache.catalina.connector.CoyoteOutputStream.flush(CoyoteOutputStream.java:98)

at com.ctc.wstx.io.UTF8Writer.flush(UTF8Writer.java:99)

at com.ctc.wstx.sw.BufferingXmlWriter.flush(BufferingXmlWriter.java:214)

at com.ctc.wstx.sw.BufferingXmlWriter.close(BufferingXmlWriter.java:194)

at com.ctc.wstx.sw.BaseStreamWriter.finishDocument(BaseStreamWriter.java:1685)

... 27 more

Caused by: java.io.IOException

at org.apache.coyote.http11.InternalAprOutputBuffer.flushBuffer(InternalAprOutputBuffer.java:716)

at org.apache.coyote.http11.InternalAprOutputBuffer.flush(InternalAprOutputBuffer.java:304)

at org.apache.coyote.http11.Http11AprProcessor.action(Http11AprProcessor.java:1021)

at org.apache.coyote.Response.action(Response.java:183)

at org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:314)

... 33 more

Any help will be greatly appreciated.

Thanks!

Alec

André Warnier

2011-08-04 17:05:18 UTC

Permalink

Hi.

It dos not look to me like the problem is in Tomcat per se, but rather in the application
running inside of Tomcat, and/or the client application.

Let me explain what leads me to that supposition :

- according to (1) and (2) below, the SOAP request was sent by the client, received by
Tomcat, and passed by Tomcat to the corresponding application

Then according to the log, an exception occurs *within the application classes* (not

Post by Alec Swan
Caused by: ClientAbortException: java.io.IOException

That would mean that when the webapp within the Tomcat application is trying to send some
output to the client, it finds the client socket closed (by the client).

This could happen for instance if the client "got tired of waiting" so to speak, hit some
internal timeout waiting for a server response, and decided to give up and close the
socket on which it was waiting for a response.
Then some time later the application tries to send some response, but hits the closed
socket and throws the exception.

That would explain (3) in your list, because from the point of view of Tomcat then, this
application invocation is finished (with an error, but finished).

Now why the application appears in (4) to still be waiting, I can only then attribute to
some logic error in the application : it gave up waiting and closed the socket, but still
says that it is waiting ?

In any case, in a standard configuration, I do not think that Tomcat would kill an
application by its own decision, even if this application took 30 minutes to return a
response.

Maybe a few thread dumps a couple of seconds apart, when Tomcat has received the SOAP
request, may explain what the responding thread is doing that takes so long before sending
a response. There is information in the Tomcat FAQ about how to do that.

I would also inspect the client code to check if there is a timeout for a server response,
and what it does exactly when that timeout is reached.
A standard browser would have a timeout of approx. 5 minutes, and then it would display a
page saying "the server is taking too long to respond.." etc..
Biut with other code, it depends on the code.

Post by Alec Swan
Hello,
We are experiencing a problem on our production servers causing our
HTTP clients to hang. I apologize for cross-posting with Metro forum
but this is a critical problem for us.
It looks like client SOAP HTTP requests get dropped/terminated by
Tomcat or metro without notifying the client that request was
terminated leaving the client waiting indefinitely for response.
1. Client makes a SOAP call to the server
2. Tomcat receives HTTP request and we can see it listed on Tomcat Manager page
3. After about 5 minutes HTTP request disappears from the list of
active HTTP request
4. The client is still waiting for response
We also noticed the following exception logged in catalina.out. It is
thrown around the same time when the problem above occurs but we are
not sure if there is a direct correlation between them.
Aug 1, 2011 12:07:44 AM
com.sun.xml.ws.transport.http.servlet.WSServletDelegate doGet
SEVERE: caught throwable
javax.xml.ws.WebServiceException: com.ctc.wstx.exc.WstxIOException: null
at com.sun.xml.ws.encoding.StreamSOAPCodec.encode(StreamSOAPCodec.java:112)
at com.sun.xml.ws.encoding.SOAPBindingCodec.encode(SOAPBindingCodec.java:278)
at com.sun.xml.ws.transport.http.HttpAdapter.encodePacket(HttpAdapter.java:383)
at com.sun.xml.ws.transport.http.HttpAdapter.access$100(HttpAdapter.java:93)
at com.sun.xml.ws.transport.http.HttpAdapter$HttpToolkit.handle(HttpAdapter.java:529)
at com.sun.xml.ws.transport.http.HttpAdapter.handle(HttpAdapter.java:288)
at com.sun.xml.ws.transport.http.servlet.ServletAdapter.handle(ServletAdapter.java:143)
at com.sun.xml.ws.transport.http.servlet.WSServletDelegate.doGet(WSServletDelegate.java:155)
at com.sun.xml.ws.transport.http.servlet.WSServletDelegate.doPost(WSServletDelegate.java:189)
at com.sun.xml.ws.transport.http.servlet.WSServlet.doPost(WSServlet.java:76)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:470)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:864)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1665)
at java.lang.Thread.run(Unknown Source)
Caused by: com.ctc.wstx.exc.WstxIOException: null
at com.ctc.wstx.sw.BaseStreamWriter.finishDocument(BaseStreamWriter.java:1687)
at com.ctc.wstx.sw.BaseStreamWriter.writeEndDocument(BaseStreamWriter.java:585)
at com.sun.xml.ws.message.saaj.SAAJMessage.writeTo(SAAJMessage.java:368)
at com.sun.xml.ws.encoding.StreamSOAPCodec.encode(StreamSOAPCodec.java:109)
... 24 more
Caused by: ClientAbortException: java.io.IOException
at org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:319)
at org.apache.catalina.connector.OutputBuffer.flush(OutputBuffer.java:288)
at org.apache.catalina.connector.CoyoteOutputStream.flush(CoyoteOutputStream.java:98)
at com.ctc.wstx.io.UTF8Writer.flush(UTF8Writer.java:99)
at com.ctc.wstx.sw.BufferingXmlWriter.flush(BufferingXmlWriter.java:214)
at com.ctc.wstx.sw.BufferingXmlWriter.close(BufferingXmlWriter.java:194)
at com.ctc.wstx.sw.BaseStreamWriter.finishDocument(BaseStreamWriter.java:1685)
... 27 more
Caused by: java.io.IOException
at org.apache.coyote.http11.InternalAprOutputBuffer.flushBuffer(InternalAprOutputBuffer.java:716)
at org.apache.coyote.http11.InternalAprOutputBuffer.flush(InternalAprOutputBuffer.java:304)
at org.apache.coyote.http11.Http11AprProcessor.action(Http11AprProcessor.java:1021)
at org.apache.coyote.Response.action(Response.java:183)
at org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:314)
... 33 more
Any help will be greatly appreciated.
Thanks!
Alec
---------------------------------------------------------------------

Alec Swan

2011-08-04 17:34:37 UTC

Permalink

Hello,

I agree that this is not a bug in Tomcat code, but I would appreciate
any help with troubleshooting this.

Let me tell you about our app. We have a thousands of Metro SOAP
clients which hit our Tomcat server. Some SOAP HTTP requests take over
an hour to process because queries take a very long time to execute in
the database. The clients are configured to never timeout waiting on
the server response.

So, I can see the following possible causes of the Client Abort
Exception logged by Tomcat:

1. The client drops its connection to the server - I would have
expected the client to get some sort of offline exception and
terminate the request. Instead, the client keeps waiting, so maybe
this is not the problem.
2. Tomcat times out (our connectionTimeout is set to 600000) and
somehow fails to write the response back.
3. Tomcat's DBCP connection pool times out

Could anybody help us enable the right kind of logging to verify the
last two possible causes? Can you think of any other ways to
troubleshoot this?

Thanks,

Alec

Post by AndrÃ© Warnier
Hi.
It dos not look to me like the problem is in Tomcat per se, but rather in
the application running inside of Tomcat, and/or the client application.
- according to (1) and (2) below, the SOAP request was sent by the client,
received by Tomcat, and passed by Tomcat to the corresponding application
Then according to the log, an exception occurs *within the application
classes* (not inside Tomcat code). Scrolling down the log, it appears that

Post by Alec Swan
Caused by: ClientAbortException: java.io.IOException

That would mean that when the webapp within the Tomcat application is trying
to send some output to the client, it finds the client socket closed (by the
client).
This could happen for instance if the client "got tired of waiting" so to
speak, hit some internal timeout waiting for a server response, and decided
to give up and close the socket on which it was waiting for a response.
Then some time later the application tries to send some response, but hits
the closed socket and throws the exception.
That would explain (3) in your list, because from the point of view of
Tomcat then, this application invocation is finished (with an error, but
finished).
Now why the application appears in (4) to still be waiting, I can only then
attribute to some logic error in the application : it gave up waiting and
closed the socket, but still says that it is waiting ?
In any case, in a standard configuration, I do not think that Tomcat would
kill an application by its own decision, even if this application took 30
minutes to return a response.
Maybe a few thread dumps a couple of seconds apart, when Tomcat has received
the SOAP request, may explain what the responding thread is doing that takes
so long before sending a response. There is information in the Tomcat FAQ
about how to do that.
I would also inspect the client code to check if there is a timeout for a
server response, and what it does exactly when that timeout is reached.
A standard browser would have a timeout of approx. 5 minutes, and then it
would display a page saying "the server is taking too long to respond.."
etc..
Biut with other code, it depends on the code.

Post by Alec Swan
Hello,
We are experiencing a problem on our production servers causing our
HTTP clients to hang. I apologize for cross-posting with Metro forum
but this is a critical problem for us.
It looks like client SOAP HTTP requests get dropped/terminated by
Tomcat or metro without notifying the client that request was
terminated leaving the client waiting indefinitely for response.
1. Client makes a SOAP call to the server
2. Tomcat receives HTTP request and we can see it listed on Tomcat Manager page
3. After about 5 minutes HTTP request disappears from the list of
active HTTP request
4. The client is still waiting for response
We also noticed the following exception logged in catalina.out. It is
thrown around the same time when the problem above occurs but we are
not sure if there is a direct correlation between them.
Aug 1, 2011 12:07:44 AM
com.sun.xml.ws.transport.http.servlet.WSServletDelegate doGet
SEVERE: caught throwable
javax.xml.ws.WebServiceException: com.ctc.wstx.exc.WstxIOException: null
at
com.sun.xml.ws.encoding.StreamSOAPCodec.encode(StreamSOAPCodec.java:112)
at
com.sun.xml.ws.encoding.SOAPBindingCodec.encode(SOAPBindingCodec.java:278)
at
com.sun.xml.ws.transport.http.HttpAdapter.encodePacket(HttpAdapter.java:383)
at
com.sun.xml.ws.transport.http.HttpAdapter.access$100(HttpAdapter.java:93)
at
com.sun.xml.ws.transport.http.HttpAdapter$HttpToolkit.handle(HttpAdapter.java:529)
at
com.sun.xml.ws.transport.http.HttpAdapter.handle(HttpAdapter.java:288)
at
com.sun.xml.ws.transport.http.servlet.ServletAdapter.handle(ServletAdapter.java:143)
at
com.sun.xml.ws.transport.http.servlet.WSServletDelegate.doGet(WSServletDelegate.java:155)
at
com.sun.xml.ws.transport.http.servlet.WSServletDelegate.doPost(WSServletDelegate.java:189)
at
com.sun.xml.ws.transport.http.servlet.WSServlet.doPost(WSServlet.java:76)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:470)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at
org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:864)
at
org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)
at
org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1665)
at java.lang.Thread.run(Unknown Source)
Caused by: com.ctc.wstx.exc.WstxIOException: null
at
com.ctc.wstx.sw.BaseStreamWriter.finishDocument(BaseStreamWriter.java:1687)
at
com.ctc.wstx.sw.BaseStreamWriter.writeEndDocument(BaseStreamWriter.java:585)
at
com.sun.xml.ws.message.saaj.SAAJMessage.writeTo(SAAJMessage.java:368)
at
com.sun.xml.ws.encoding.StreamSOAPCodec.encode(StreamSOAPCodec.java:109)
... 24 more
Caused by: ClientAbortException: java.io.IOException
at
org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:319)
at
org.apache.catalina.connector.OutputBuffer.flush(OutputBuffer.java:288)
at
org.apache.catalina.connector.CoyoteOutputStream.flush(CoyoteOutputStream.java:98)
at com.ctc.wstx.io.UTF8Writer.flush(UTF8Writer.java:99)
at
com.ctc.wstx.sw.BufferingXmlWriter.flush(BufferingXmlWriter.java:214)
at
com.ctc.wstx.sw.BufferingXmlWriter.close(BufferingXmlWriter.java:194)
at
com.ctc.wstx.sw.BaseStreamWriter.finishDocument(BaseStreamWriter.java:1685)
... 27 more
Caused by: java.io.IOException
at
org.apache.coyote.http11.InternalAprOutputBuffer.flushBuffer(InternalAprOutputBuffer.java:716)
at
org.apache.coyote.http11.InternalAprOutputBuffer.flush(InternalAprOutputBuffer.java:304)
at
org.apache.coyote.http11.Http11AprProcessor.action(Http11AprProcessor.java:1021)
at org.apache.coyote.Response.action(Response.java:183)
at
org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:314)
... 33 more
Any help will be greatly appreciated.
Thanks!
Alec
---------------------------------------------------------------------

---------------------------------------------------------------------

Rainer Jung

2011-08-04 17:52:21 UTC

Permalink

Post by Alec Swan
Hello,
I agree that this is not a bug in Tomcat code, but I would appreciate
any help with troubleshooting this.
Let me tell you about our app. We have a thousands of Metro SOAP
clients which hit our Tomcat server. Some SOAP HTTP requests take over
an hour to process because queries take a very long time to execute in
the database. The clients are configured to never timeout waiting on
the server response.
So, I can see the following possible causes of the Client Abort
1. The client drops its connection to the server - I would have
expected the client to get some sort of offline exception and
terminate the request. Instead, the client keeps waiting, so maybe
this is not the problem.
2. Tomcat times out (our connectionTimeout is set to 600000) and
somehow fails to write the response back.
3. Tomcat's DBCP connection pool times out
Could anybody help us enable the right kind of logging to verify the
last two possible causes? Can you think of any other ways to
troubleshoot this?

If it is easily reproducible, you can sniff network traffic and see,
which side closes the connection.

Regards,

Rainer

André Warnier

2011-08-04 19:52:33 UTC

Permalink

And could there be something else, between the client and the Tomcat, which could time out
if no activity happens on that connection ?
(I have known of routers/firewalls which did this, to save on connections to maintain).

Post by Alec Swan
So, I can see the following possible causes of the Client Abort
1. The client drops its connection to the server - I would have
expected the client to get some sort of offline exception and
terminate the request. Instead, the client keeps waiting, so maybe
this is not the problem.
2. Tomcat times out (our connectionTimeout is set to 600000) and
somehow fails to write the response back.

I think that you can rule this one out. The connectionTimeout, if I remember correctly,
only applies to the time between
- when the client establishes the HTTP connection to Tomcat
- and the time when Tomcat receives the actual request on that connection
It is essentially meant to avoid attacks where many clients would create connections to
Tomcat and never send a request (and thus block threads (or at least connected sockets)
for nothing).

But check the documentation to see if maybe this parameter value is taken as a default for
other unspecified timeouts.

Post by Alec Swan
3. Tomcat's DBCP connection pool times out
Could anybody help us enable the right kind of logging to verify the
last two possible causes? Can you think of any other ways to
troubleshoot this?

You can set up an AccessLogValve and measure the time taken by each request.
And you can take thread dumps, as mentioned previously, to see what these Tomcat threads
are really doing while the client is waiting.
You can also trace the real packets exchanged via an external protocol analyser such as
Wireshark. That will tell you if it is the client dropping the connection, or if something
in-between is doing that. Tomcat logs can only tell you what happens in Tomcat.
And for Tomcat, if an intermediate agent is dropping the connection, it will also look
like a Client Abort.

Generally speaking, I don't think that there are many explanations for a "Client Abort"
exception. If it was Tomcat doing (or not doing) something and aborting the application,
the error message would be different.
So, considering that this is a clue, and that you have no other clue until now, I would
start by examining that as a possible cause, and not other hypothetical scenarios for
which you have not seen a clue yet.

Post by Alec Swan
Thanks,
Alec

Post by Alec Swan
Caused by: ClientAbortException: java.io.IOException

That would mean that when the webapp within the Tomcat application is trying
to send some output to the client, it finds the client socket closed (by the
client).
This could happen for instance if the client "got tired of waiting" so to
speak, hit some internal timeout waiting for a server response, and decided
to give up and close the socket on which it was waiting for a response.
Then some time later the application tries to send some response, but hits
the closed socket and throws the exception.
That would explain (3) in your list, because from the point of view of
Tomcat then, this application invocation is finished (with an error, but
finished).
Now why the application appears in (4) to still be waiting, I can only then
attribute to some logic error in the application : it gave up waiting and
closed the socket, but still says that it is waiting ?
In any case, in a standard configuration, I do not think that Tomcat would
kill an application by its own decision, even if this application took 30
minutes to return a response.
Maybe a few thread dumps a couple of seconds apart, when Tomcat has received
the SOAP request, may explain what the responding thread is doing that takes
so long before sending a response. There is information in the Tomcat FAQ
about how to do that.
I would also inspect the client code to check if there is a timeout for a
server response, and what it does exactly when that timeout is reached.
A standard browser would have a timeout of approx. 5 minutes, and then it
would display a page saying "the server is taking too long to respond.."
etc..
Biut with other code, it depends on the code.

Post by Alec Swan
Hello,
We are experiencing a problem on our production servers causing our
HTTP clients to hang. I apologize for cross-posting with Metro forum
but this is a critical problem for us.
It looks like client SOAP HTTP requests get dropped/terminated by
Tomcat or metro without notifying the client that request was
terminated leaving the client waiting indefinitely for response.
1. Client makes a SOAP call to the server
2. Tomcat receives HTTP request and we can see it listed on Tomcat Manager page
3. After about 5 minutes HTTP request disappears from the list of
active HTTP request
4. The client is still waiting for response
We also noticed the following exception logged in catalina.out. It is
thrown around the same time when the problem above occurs but we are
not sure if there is a direct correlation between them.
Aug 1, 2011 12:07:44 AM
com.sun.xml.ws.transport.http.servlet.WSServletDelegate doGet
SEVERE: caught throwable
javax.xml.ws.WebServiceException: com.ctc.wstx.exc.WstxIOException: null
at
com.sun.xml.ws.encoding.StreamSOAPCodec.encode(StreamSOAPCodec.java:112)
at
com.sun.xml.ws.encoding.SOAPBindingCodec.encode(SOAPBindingCodec.java:278)
at
com.sun.xml.ws.transport.http.HttpAdapter.encodePacket(HttpAdapter.java:383)
at
com.sun.xml.ws.transport.http.HttpAdapter.access$100(HttpAdapter.java:93)
at
com.sun.xml.ws.transport.http.HttpAdapter$HttpToolkit.handle(HttpAdapter.java:529)
at
com.sun.xml.ws.transport.http.HttpAdapter.handle(HttpAdapter.java:288)
at
com.sun.xml.ws.transport.http.servlet.ServletAdapter.handle(ServletAdapter.java:143)
at
com.sun.xml.ws.transport.http.servlet.WSServletDelegate.doGet(WSServletDelegate.java:155)
at
com.sun.xml.ws.transport.http.servlet.WSServletDelegate.doPost(WSServletDelegate.java:189)
at
com.sun.xml.ws.transport.http.servlet.WSServlet.doPost(WSServlet.java:76)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:470)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at
org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:864)
at
org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)
at
org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1665)
at java.lang.Thread.run(Unknown Source)
Caused by: com.ctc.wstx.exc.WstxIOException: null
at
com.ctc.wstx.sw.BaseStreamWriter.finishDocument(BaseStreamWriter.java:1687)
at
com.ctc.wstx.sw.BaseStreamWriter.writeEndDocument(BaseStreamWriter.java:585)
at
com.sun.xml.ws.message.saaj.SAAJMessage.writeTo(SAAJMessage.java:368)
at
com.sun.xml.ws.encoding.StreamSOAPCodec.encode(StreamSOAPCodec.java:109)
... 24 more
Caused by: ClientAbortException: java.io.IOException
at
org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:319)
at
org.apache.catalina.connector.OutputBuffer.flush(OutputBuffer.java:288)
at
org.apache.catalina.connector.CoyoteOutputStream.flush(CoyoteOutputStream.java:98)
at com.ctc.wstx.io.UTF8Writer.flush(UTF8Writer.java:99)
at
com.ctc.wstx.sw.BufferingXmlWriter.flush(BufferingXmlWriter.java:214)
at
com.ctc.wstx.sw.BufferingXmlWriter.close(BufferingXmlWriter.java:194)
at
com.ctc.wstx.sw.BaseStreamWriter.finishDocument(BaseStreamWriter.java:1685)
... 27 more
Caused by: java.io.IOException
at
org.apache.coyote.http11.InternalAprOutputBuffer.flushBuffer(InternalAprOutputBuffer.java:716)
at
org.apache.coyote.http11.InternalAprOutputBuffer.flush(InternalAprOutputBuffer.java:304)
at
org.apache.coyote.http11.Http11AprProcessor.action(Http11AprProcessor.java:1021)
at org.apache.coyote.Response.action(Response.java:183)
at
org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:314)
... 33 more
Any help will be greatly appreciated.
Thanks!
Alec
---------------------------------------------------------------------

---------------------------------------------------------------------

Alec Swan

2011-08-04 21:16:31 UTC

Permalink

Thank you all for your suggestions.

I've been sniffing TCP traffic all day today and noticed the following pattern:
1. Client sends an HTTP post to Tomcat
2. Tomcat receives the request and takes 15 minutes to process it
3. Tomcat eventually completes the request and attempts to write it
back to the client
4. Client never receives the response

So, you are right that the connection is dropped somewhere between the
client and Tomcat. I removed the load balancer from the equation by
hitting the app server directly.

I am troubleshooting this in our customer's environment and have no
idea how to go about tracking down where the connection gets dropped.
I guess we could somehow track network hops? Any ideas on how to track
this down?

Thanks,

Alec

Post by AndrÃ© Warnier

And could there be something else, between the client and the Tomcat, which
could time out if no activity happens on that connection ?
(I have known of routers/firewalls which did this, to save on connections to maintain).

I think that you can rule this one out. The connectionTimeout, if I
remember correctly, only applies to the time between
- when the client establishes the HTTP connection to Tomcat
- and the time when Tomcat receives the actual request on that connection
It is essentially meant to avoid attacks where many clients would create
connections to Tomcat and never send a request (and thus block threads (or
at least connected sockets) for nothing).
But check the documentation to see if maybe this parameter value is taken as
a default for other unspecified timeouts.

You can set up an AccessLogValve and measure the time taken by each request.
And you can take thread dumps, as mentioned previously, to see what these
Tomcat threads are really doing while the client is waiting.
You can also trace the real packets exchanged via an external protocol
analyser such as Wireshark. That will tell you if it is the client dropping
the connection, or if something in-between is doing that. Tomcat logs can
only tell you what happens in Tomcat.
And for Tomcat, if an intermediate agent is dropping the connection, it will
also look like a Client Abort.
Generally speaking, I don't think that there are many explanations for a
"Client Abort" exception. If it was Tomcat doing (or not doing) something
and aborting the application, the error message would be different.
So, considering that this is a clue, and that you have no other clue until
now, I would start by examining that as a possible cause, and not other
hypothetical scenarios for which you have not seen a clue yet.

Post by Alec Swan
Thanks,
Alec

Post by Alec Swan
Caused by: ClientAbortException: java.io.IOException

That would mean that when the webapp within the Tomcat application is trying
to send some output to the client, it finds the client socket closed (by the
client).
This could happen for instance if the client "got tired of waiting" so to
speak, hit some internal timeout waiting for a server response, and decided
to give up and close the socket on which it was waiting for a response.
Then some time later the application tries to send some response, but hits
the closed socket and throws the exception.
That would explain (3) in your list, because from the point of view of
Tomcat then, this application invocation is finished (with an error, but
finished).
Now why the application appears in (4) to still be waiting, I can only then
attribute to some logic error in the application : it gave up waiting and
closed the socket, but still says that it is waiting ?
In any case, in a standard configuration, I do not think that Tomcat would
kill an application by its own decision, even if this application took 30
minutes to return a response.
Maybe a few thread dumps a couple of seconds apart, when Tomcat has received
the SOAP request, may explain what the responding thread is doing that takes
so long before sending a response. There is information in the Tomcat FAQ
about how to do that.
I would also inspect the client code to check if there is a timeout for a
server response, and what it does exactly when that timeout is reached.
A standard browser would have a timeout of approx. 5 minutes, and then it
would display a page saying "the server is taking too long to respond.."
etc..
Biut with other code, it depends on the code.

Post by Alec Swan
Hello,
We are experiencing a problem on our production servers causing our
HTTP clients to hang. I apologize for cross-posting with Metro forum
but this is a critical problem for us.
It looks like client SOAP HTTP requests get dropped/terminated by
Tomcat or metro without notifying the client that request was
terminated leaving the client waiting indefinitely for response.
1. Client makes a SOAP call to the server
2. Tomcat receives HTTP request and we can see it listed on Tomcat
Manager
page
3. After about 5 minutes HTTP request disappears from the list of
active HTTP request
4. The client is still waiting for response
We also noticed the following exception logged in catalina.out. It is
thrown around the same time when the problem above occurs but we are
not sure if there is a direct correlation between them.
Aug 1, 2011 12:07:44 AM
com.sun.xml.ws.transport.http.servlet.WSServletDelegate doGet
SEVERE: caught throwable
javax.xml.ws.WebServiceException: com.ctc.wstx.exc.WstxIOException: null
at
com.sun.xml.ws.encoding.StreamSOAPCodec.encode(StreamSOAPCodec.java:112)
at
com.sun.xml.ws.encoding.SOAPBindingCodec.encode(SOAPBindingCodec.java:278)
at
com.sun.xml.ws.transport.http.HttpAdapter.encodePacket(HttpAdapter.java:383)
at
com.sun.xml.ws.transport.http.HttpAdapter.access$100(HttpAdapter.java:93)
at
com.sun.xml.ws.transport.http.HttpAdapter$HttpToolkit.handle(HttpAdapter.java:529)
at
com.sun.xml.ws.transport.http.HttpAdapter.handle(HttpAdapter.java:288)
at
com.sun.xml.ws.transport.http.servlet.ServletAdapter.handle(ServletAdapter.java:143)
at
com.sun.xml.ws.transport.http.servlet.WSServletDelegate.doGet(WSServletDelegate.java:155)
at
com.sun.xml.ws.transport.http.servlet.WSServletDelegate.doPost(WSServletDelegate.java:189)
at
com.sun.xml.ws.transport.http.servlet.WSServlet.doPost(WSServlet.java:76)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:470)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at
org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:864)
at
org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)
at
org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1665)
at java.lang.Thread.run(Unknown Source)
Caused by: com.ctc.wstx.exc.WstxIOException: null
at
com.ctc.wstx.sw.BaseStreamWriter.finishDocument(BaseStreamWriter.java:1687)
at
com.ctc.wstx.sw.BaseStreamWriter.writeEndDocument(BaseStreamWriter.java:585)
at
com.sun.xml.ws.message.saaj.SAAJMessage.writeTo(SAAJMessage.java:368)
at
com.sun.xml.ws.encoding.StreamSOAPCodec.encode(StreamSOAPCodec.java:109)
... 24 more
Caused by: ClientAbortException: java.io.IOException
at
org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:319)
at
org.apache.catalina.connector.OutputBuffer.flush(OutputBuffer.java:288)
at
org.apache.catalina.connector.CoyoteOutputStream.flush(CoyoteOutputStream.java:98)
at com.ctc.wstx.io.UTF8Writer.flush(UTF8Writer.java:99)
at
com.ctc.wstx.sw.BufferingXmlWriter.flush(BufferingXmlWriter.java:214)
at
com.ctc.wstx.sw.BufferingXmlWriter.close(BufferingXmlWriter.java:194)
at
com.ctc.wstx.sw.BaseStreamWriter.finishDocument(BaseStreamWriter.java:1685)
... 27 more
Caused by: java.io.IOException
at
org.apache.coyote.http11.InternalAprOutputBuffer.flushBuffer(InternalAprOutputBuffer.java:716)
at
org.apache.coyote.http11.InternalAprOutputBuffer.flush(InternalAprOutputBuffer.java:304)
at
org.apache.coyote.http11.Http11AprProcessor.action(Http11AprProcessor.java:1021)
at org.apache.coyote.Response.action(Response.java:183)
at
org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:314)
... 33 more
Any help will be greatly appreciated.
Thanks!
Alec
---------------------------------------------------------------------

---------------------------------------------------------------------

Alec Swan

2011-08-04 21:27:37 UTC

Permalink

Here is a little more information.

Tomcat was processing HTTP request for 10 minutes sharp and was
eventually ready to send the response back to the client. So, Tomcat
generated a TCP [FIN, ACK] message with a valid SOAP response.
However, the very next TCP message contained the following error:

"Broken TCP. The acknowledge field is nonzero while the ACK flag is not set."

Thanks,

Alec

Post by Alec Swan
Thank you all for your suggestions.
1. Client sends an HTTP post to Tomcat
2. Tomcat receives the request and takes 15 minutes to process it
3. Tomcat eventually completes the request and attempts to write it
back to the client
4. Client never receives the response
So, you are right that the connection is dropped somewhere between the
client and Tomcat. I removed the load balancer from the equation by
hitting the app server directly.
I am troubleshooting this in our customer's environment and have no
idea how to go about tracking down where the connection gets dropped.
I guess we could somehow track network hops? Any ideas on how to track
this down?
Thanks,
Alec

And could there be something else, between the client and the Tomcat, which
could time out if no activity happens on that connection ?
(I have known of routers/firewalls which did this, to save on connections to maintain).

I think that you can rule this one out. The connectionTimeout, if I
remember correctly, only applies to the time between
- when the client establishes the HTTP connection to Tomcat
- and the time when Tomcat receives the actual request on that connection
It is essentially meant to avoid attacks where many clients would create
connections to Tomcat and never send a request (and thus block threads (or
at least connected sockets) for nothing).
But check the documentation to see if maybe this parameter value is taken as
a default for other unspecified timeouts.

You can set up an AccessLogValve and measure the time taken by each request.
And you can take thread dumps, as mentioned previously, to see what these
Tomcat threads are really doing while the client is waiting.
You can also trace the real packets exchanged via an external protocol
analyser such as Wireshark. That will tell you if it is the client dropping
the connection, or if something in-between is doing that. Tomcat logs can
only tell you what happens in Tomcat.
And for Tomcat, if an intermediate agent is dropping the connection, it will
also look like a Client Abort.
Generally speaking, I don't think that there are many explanations for a
"Client Abort" exception. If it was Tomcat doing (or not doing) something
and aborting the application, the error message would be different.
So, considering that this is a clue, and that you have no other clue until
now, I would start by examining that as a possible cause, and not other
hypothetical scenarios for which you have not seen a clue yet.

Post by Alec Swan
Thanks,
Alec

Post by Alec Swan
Caused by: ClientAbortException: java.io.IOException

That would mean that when the webapp within the Tomcat application is trying
to send some output to the client, it finds the client socket closed (by the
client).
This could happen for instance if the client "got tired of waiting" so to
speak, hit some internal timeout waiting for a server response, and decided
to give up and close the socket on which it was waiting for a response.
Then some time later the application tries to send some response, but hits
the closed socket and throws the exception.
That would explain (3) in your list, because from the point of view of
Tomcat then, this application invocation is finished (with an error, but
finished).
Now why the application appears in (4) to still be waiting, I can only then
attribute to some logic error in the application : it gave up waiting and
closed the socket, but still says that it is waiting ?
In any case, in a standard configuration, I do not think that Tomcat would
kill an application by its own decision, even if this application took 30
minutes to return a response.
Maybe a few thread dumps a couple of seconds apart, when Tomcat has received
the SOAP request, may explain what the responding thread is doing that takes
so long before sending a response. There is information in the Tomcat FAQ
about how to do that.
I would also inspect the client code to check if there is a timeout for a
server response, and what it does exactly when that timeout is reached.
A standard browser would have a timeout of approx. 5 minutes, and then it
would display a page saying "the server is taking too long to respond.."
etc..
Biut with other code, it depends on the code.

Post by Alec Swan
Hello,
We are experiencing a problem on our production servers causing our
HTTP clients to hang. I apologize for cross-posting with Metro forum
but this is a critical problem for us.
It looks like client SOAP HTTP requests get dropped/terminated by
Tomcat or metro without notifying the client that request was
terminated leaving the client waiting indefinitely for response.
1. Client makes a SOAP call to the server
2. Tomcat receives HTTP request and we can see it listed on Tomcat
Manager
page
3. After about 5 minutes HTTP request disappears from the list of
active HTTP request
4. The client is still waiting for response
We also noticed the following exception logged in catalina.out. It is
thrown around the same time when the problem above occurs but we are
not sure if there is a direct correlation between them.
Aug 1, 2011 12:07:44 AM
com.sun.xml.ws.transport.http.servlet.WSServletDelegate doGet
SEVERE: caught throwable
javax.xml.ws.WebServiceException: com.ctc.wstx.exc.WstxIOException: null
at
com.sun.xml.ws.encoding.StreamSOAPCodec.encode(StreamSOAPCodec.java:112)
at
com.sun.xml.ws.encoding.SOAPBindingCodec.encode(SOAPBindingCodec.java:278)
at
com.sun.xml.ws.transport.http.HttpAdapter.encodePacket(HttpAdapter.java:383)
at
com.sun.xml.ws.transport.http.HttpAdapter.access$100(HttpAdapter.java:93)
at
com.sun.xml.ws.transport.http.HttpAdapter$HttpToolkit.handle(HttpAdapter.java:529)
at
com.sun.xml.ws.transport.http.HttpAdapter.handle(HttpAdapter.java:288)
at
com.sun.xml.ws.transport.http.servlet.ServletAdapter.handle(ServletAdapter.java:143)
at
com.sun.xml.ws.transport.http.servlet.WSServletDelegate.doGet(WSServletDelegate.java:155)
at
com.sun.xml.ws.transport.http.servlet.WSServletDelegate.doPost(WSServletDelegate.java:189)
at
com.sun.xml.ws.transport.http.servlet.WSServlet.doPost(WSServlet.java:76)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:470)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at
org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:864)
at
org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)
at
org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1665)
at java.lang.Thread.run(Unknown Source)
Caused by: com.ctc.wstx.exc.WstxIOException: null
at
com.ctc.wstx.sw.BaseStreamWriter.finishDocument(BaseStreamWriter.java:1687)
at
com.ctc.wstx.sw.BaseStreamWriter.writeEndDocument(BaseStreamWriter.java:585)
at
com.sun.xml.ws.message.saaj.SAAJMessage.writeTo(SAAJMessage.java:368)
at
com.sun.xml.ws.encoding.StreamSOAPCodec.encode(StreamSOAPCodec.java:109)
... 24 more
Caused by: ClientAbortException: java.io.IOException
at
org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:319)
at
org.apache.catalina.connector.OutputBuffer.flush(OutputBuffer.java:288)
at
org.apache.catalina.connector.CoyoteOutputStream.flush(CoyoteOutputStream.java:98)
at com.ctc.wstx.io.UTF8Writer.flush(UTF8Writer.java:99)
at
com.ctc.wstx.sw.BufferingXmlWriter.flush(BufferingXmlWriter.java:214)
at
com.ctc.wstx.sw.BufferingXmlWriter.close(BufferingXmlWriter.java:194)
at
com.ctc.wstx.sw.BaseStreamWriter.finishDocument(BaseStreamWriter.java:1685)
... 27 more
Caused by: java.io.IOException
at
org.apache.coyote.http11.InternalAprOutputBuffer.flushBuffer(InternalAprOutputBuffer.java:716)
at
org.apache.coyote.http11.InternalAprOutputBuffer.flush(InternalAprOutputBuffer.java:304)
at
org.apache.coyote.http11.Http11AprProcessor.action(Http11AprProcessor.java:1021)
at org.apache.coyote.Response.action(Response.java:183)
at
org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:314)
... 33 more
Any help will be greatly appreciated.
Thanks!
Alec
---------------------------------------------------------------------

---------------------------------------------------------------------

Rainer Jung

2011-08-04 17:35:16 UTC

Permalink

300 seconds sounds like the default Timeout of the Apache Web Server. Is
there an Apache reverse proxy or something similar between the Client
and Tomcat?

As André said: Tomcat has no Timeout on processing the request. If the
request is received and the servlet is processing it, it will not
interrupt it, close the connection or similar.

Regards,

Rainer