Stateless Session EJB hangs using URLConnection but WLS doesn't clean up

Question

Hi
We have a stateless session EJB running under WLS 5.1 with service
pack 10 on Solaris.
The bean calls a remote HTTP server using the java.net.URLConnection
class and forwards the response to the EJB client. The bean is largely
working fine but some threads hang waiting on the HTTP response. Debug
statements, which are written immediately after the response has been
read and the connection has been closed, do not appear in our log for
the hung threads. The WebLogic Console displays these threads as "in
use" and a "netstat -an" displays the tcp connections as ESTABLISHED.
However, the access logs of the remote Apache server show the HTTP
connections of the threads in question completed successfully with
HTTP code 200. The Apache server is using keep-alive connections.
Some EJB threads are still waiting for something it seems.
Has anyody else experienced this when using URLConnection from
stateless session EJBs under WLS?
The second problem is why doesn't WLS time these threads out after
trans-timeout-seconds (we're using the default of 300 seconds)? The
WLS log shows no error messages relating to this problem.
I'm grateful for any info offered.
Thanks in advance
Steve

Answer 1

If you suspect that WLS protocol handler is at fault (and quite often it is),
one thing to try is (if you use Sun's JVM) to use Sun's HTTP protocol handler
instead of WLS (the most common symptom is when code which makes HTTP requests
works fine outside of WebLogic and you have problems getting it to work inside
WebLogic) :
replace
URL url = new URL("http://...");
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
with
URL url = new URL(null, "http://...", new sun.net.www.protocol.http.Handler());
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
You will have to edit weblogic.policy to allow your code to specify protocol
handler.
Also note that transaction timeout is only checked on method boundaries, or
when your code attempts to do something with the database - it is not going to
interrupt thread which is waiting for HTTP response.
Steve Lock <[email protected]> wrote:
Hi
Thanks for the info. The remote HTTP server's access log shows that
the requests were successfully processed. Doesn't this mean that the
connection is then closed? I know the web server is using keep-alive
connections but I thought this was transparent to the client...?
Also why doesn't WLS remove the hung threads?
Steve
"Ignacio G. Dupont" <[email protected]> wrote in message news:<[email protected]>...
We have had a problem like yours with Weblogic 6.1 SP2 on Linux
The problem is sun's implementation of the HTTP connections doesn't have a
timeout, so if the other peer doesn't close the connection your threads will
be "locked" on the connection.
We have found searching the web that the Jakarta project has a package
called Jakarta commons that implements HTTP connections with an
setSoTimeout(int timeout) method so you can open the connections with your
desired timeout. You have to download the code from the CVS as the released
version doesn't support the timedout sockets yet.
When support for the JDK 1.4 version will be announced by Bea you could use
one of its new features that will allow you to pass arguments to the JVM to
specify the maximum socket connection stablising timeout and the max
inactivity on the socket too.
Hope it helps you.
Dimitri