db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Kathey Marsden (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-5328) The private fields of the NetServlet can be changed by multiple threads, giving rise to race conditions and corruptions.
Date Wed, 13 Jul 2011 16:31:00 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5328?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13064677#comment-13064677
] 

Kathey Marsden commented on DERBY-5328:
---------------------------------------

What  corruptions that might be caused by this issue?  Could an actual database corruption
occur or is it just that the output screens might be garbled when presented to the user?


> The private fields of the NetServlet can be changed by multiple threads, giving rise
to race conditions and corruptions.
> ------------------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-5328
>                 URL: https://issues.apache.org/jira/browse/DERBY-5328
>             Project: Derby
>          Issue Type: Bug
>          Components: Network Server
>    Affects Versions: 10.9.0.0
>            Reporter: Rick Hillegas
>
> At the beginning of the NetServlet class, there are a number of private fields. These
fields can be inspected and changed by any thread running inside NetServlet.doGet(). Due to
the way that app servers dispatch servlet requests, this means that multiple threads can be
operating inside doGet() at the same time, clobbering one another's work. The weirdest instance
of this is the shared PrintWriter (called "out") which is used to produce the response web
page sent back by the servlet. Multiple threads all writing to the same PrintWriter will create
a very bizarre response page. The following improvements should be made:
> 1) The "server" field should be set by a synchronized method.
> 2) Every run through doGet() should create its own PrintWriter which is passed to other
methods. The instance-wide "out" field should be removed.
> 3) Various other fields should be re-coded using the Atomic classes introduced by Java
5. These fields include "logStatus" and "traceStatus". This solution can be implemented if
the community votes to approve the sunsetting of JVM 1.4 (currently at the polls).

--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira

        

Mime
View raw message