DO NOT REPLY [Bug 41706] New: - StandardWrapper uses double-checked locking

[bugzilla]

DO NOT REPLY TO THIS EMAIL, BUT PLEASE POST YOUR BUG·
RELATED COMMENTS THROUGH THE WEB INTERFACE AVAILABLE AT
<http://issues.apache.org/bugzilla/show_bug.cgi?id=41706>.
ANY REPLY MADE TO THIS MESSAGE WILL NOT BE COLLECTED AND·
INSERTED IN THE BUG DATABASE.

http://issues.apache.org/bugzilla/show_bug.cgi?id=41706

           Summary: StandardWrapper uses double-checked locking
           Product: Tomcat 5
           Version: 5.5.20
          Platform: Other
        OS/Version: other
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Catalina
        AssignedTo: tomcat-dev@jakarta.apache.org
        ReportedBy: [EMAIL PROTECTED]


StandardWrapper.allocate includes the following code:

            // Load and initialize our instance if necessary
            if (instance == null) {
                synchronized (this) {
                    if (instance == null) {
                        try {
                            if (log.isDebugEnabled())
                                log.debug("Allocating non-STM instance");

                            instance = loadServlet();
                        } catch (ServletException e) {
                            throw e;
                        } catch (Throwable e) {
                            throw new ServletException
                                (sm.getString("standardWrapper.allocate"), e);
                        }
                    }
                }
            }

The behavior of the null check before the synchronized block is unspecified, and
can fail.

The additional check should be removed leaving only the check within the
synchronized block:

            // Load and initialize our instance if necessary
            synchronized (this) {
                if (instance == null) {
                    try {
                        if (log.isDebugEnabled())
                            log.debug("Allocating non-STM instance");

                        instance = loadServlet();
                    } catch (ServletException e) {
                        throw e;
                    } catch (Throwable e) {
                        throw new ServletException
                            (sm.getString("standardWrapper.allocate"), e);
                    }
                }
            }

-- 
Configure bugmail: http://issues.apache.org/bugzilla/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug, or are watching the assignee.

---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]