[Bug 58702] New: Access log lines are not written if client aborts

[bu...@apache.org]

https://bz.apache.org/bugzilla/show_bug.cgi?id=58702

            Bug ID: 58702
           Summary: Access log lines are not written if client aborts
           Product: Tomcat 8
           Version: 8.0.30
          Hardware: PC
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Catalina
          Assignee: dev@tomcat.apache.org
          Reporter: zikfat@gmail.com

Created attachment 33333
  --> https://bz.apache.org/bugzilla/attachment.cgi?id=33333&action=edit
war file to demo the issue

When a client aborts a request to a web application before the response is
written no line is written to the Tomcat access log.

I most recently tested this on an out-of-the-box 8.0.30 distribution but I have
seen the problem occur on Tomcat 8.0.28 and 7.0.39 as well.

I believe that the general repro steps are as simple as this:

1) In a browser, hit any endpoint in a web application that has an
AccessLogValve configured
2) Close the browser tab that made the request before the request finishes
3) Check the access log and note that no access log line was written for the
request

Demo app:
I've attached a WAR file with a simple web application to demonstrate the
problem. The source code for the application is included in the WAR.

The demo application has two servlets, one "fast" and one "slow". They both log
a unique ID for the request to a logback-configured application log, then
return a 200 response with a simple string. The only difference between them is
that the fast servlet returns immediately while the slow servlet sleeps for 30
seconds before returning.

The unique request ID generated by these servlets is also added as a request
attribute so that it can be shown in the access log.

Repro steps with the demo app:
1) Put the WAR file into a Tomcat container and load it.
2) Open a web browser and go to localhost:<port>/missing-access-log-demo/fast
3) Check the application and access logs at
<catalina-base>/logs/missing-access-log-demo. Note that both logs generated a
line for the request, and that the unique identifier for the request is the
same in both files.
4) In a web browser, go to localhost:<port>/missing-access-log-demo/slow. Watch
the application log as you make the request and you should see a line quickly
added with the request's unique ID.
5) Before the request completes, close the browser tab that made the request.
6) Wait 30 seconds and watch the access log. Note that no line for this request
is ever added.

Expected result:

Even if the client never gets the response, a request was processed by the
server so I would expect to see it appear in the access logs.

Details:
I've stepped into the Tomcat code and it seems pretty clear this is happening
in the CoyoteAdapter class:

http://svn.apache.org/viewvc/tomcat/tc8.0.x/tags/TOMCAT_8_0_30/java/org/apache/catalina/connector/CoyoteAdapter.java?view=markup

On line 558 the CoyoteAdapter calls response.finishResponse, right before the
code that will call the access log. If the client is gone the finishResponse
method throws an IOException when trying to flush its OutputBuffer. This
exception causes the code to skip the call to context.logAccess and is then
swallowed and ignored by the subsequent catch block.

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[Bug 58702] Access log lines are not written if client aborts

[bu...@apache.org]

https://bz.apache.org/bugzilla/show_bug.cgi?id=58702

Mark Thomas <ma...@apache.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 OS|                            |All
         Resolution|---                         |FIXED

--- Comment #1 from Mark Thomas <ma...@apache.org> ---
Fixed in 9.0.x for 9.0.0.M2, 8.0.x for 8.0.31 and 7.0.x for 7.0.68.

It was not fixed in 6.0.x since 6.0.x does not have the additional access log
infrastructure required.

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