Jetty

NPE on shutdown, regular thread pool

Details

  • Type: Bug Bug
  • Status: Resolved Resolved
  • Priority: Major Major
  • Resolution: Fixed
  • Affects Version/s: 6.1.4, 6.1.5rc0
  • Fix Version/s: 6.1.5
  • Component/s: None
  • Labels:
    None
  • Environment:
    Windows XP, JDK 1.6
  • Testcase included:
    yes
  • Number of attachments :
    3

Description

NullPointerException thrown when Server.stop() called. I do not know why the entire stack trace did not get printed.

We're embedding Jetty in our app. The code that started Jetty is attached. To duplicate the error, start Jetty, and then call the stop() method.

2007-07-18 15:20:32.726::INFO: Logging to STDERR via org.mortbay.log.StdErrLog
2007-07-18 15:20:32.757::INFO: jetty-6.1.5rc0
2007-07-18 15:20:32.054::INFO: Opened C:\XXX\trunk\projects\admin\logs\reque
st\2007_07_18.request.log
2007-07-18 15:20:32.070::INFO: Started SelectChannelConnector@0.0.0.0:8080
Stopping...
2007-07-18 15:20:36.362::WARN: 1 threads could not be stopped
Stopped.
2007-07-18 15:20:36.362::WARN: EXCEPTION
java.lang.NullPointerException
at org.mortbay.jetty.servlet.HashSessionManager.getSession(HashSessionMa
nager.java:222)
at org.mortbay.jetty.servlet.AbstractSessionManager.getHttpSession(Abstr
actSessionManager.java:237)
at org.mortbay.jetty.Request.getSession(Request.java:998)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:1
92)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:7
12)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)

at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHand
lerCollection.java:211)
at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.
java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:1
39)
at org.mortbay.jetty.Server.handle(Server.java:313)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:50
6)
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpCo
nnection.java:830)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:514)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:381)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.ja
va:396)
at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool
.java:442)

  1. File
    index.jsp
    10/Aug/07 4:15 PM
    0.4 kB
    Chris Cleveland
  2. Java Source File
    JettyInvokerNew.java
    18/Jul/07 3:25 PM
    5 kB
    Chris Cleveland
  3. Java Source File
    JettyInvokerX.java
    10/Aug/07 4:14 PM
    1 kB
    Chris Cleveland

Activity

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Jan Bartel added a comment -

David,
Can you verify if this is the same issue you are seeing with graceful shutdown on windows?

thanks
Jan

Show
Jan Bartel added a comment - David, Can you verify if this is the same issue you are seeing with graceful shutdown on windows? thanks Jan
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David Yu added a comment -

Jan,

This is not the same issue with graceful shutdown on windows..

David

Show
David Yu added a comment - Jan, This is not the same issue with graceful shutdown on windows.. David
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David Yu added a comment -

Chris,

I used your JettyInvokerNew.java and found out there were compilation errors. "org.mortbay.thread.concurrent.ThreadPool" does not exist.
Anyway so I edited it but still I could not replicate your error.

What webapps were deployed when you started the server?
Before you stopped the server, did you access the deployed webapps on your browser?

David

Show
David Yu added a comment - Chris, I used your JettyInvokerNew.java and found out there were compilation errors. "org.mortbay.thread.concurrent.ThreadPool" does not exist. Anyway so I edited it but still I could not replicate your error. What webapps were deployed when you started the server? Before you stopped the server, did you access the deployed webapps on your browser? David
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Chris Cleveland added a comment -

David,

org.mortbay.thread.concurrent.ThreadPool should only have been referenced in the import statement. I wonder if the fact that it was on the classpath makes any difference?

There were two webapps deployed: "root", which just contains a redirect to the "admin" webapp. There's nothing unusual in either. When the app starts, I open a browser to http://localhost:8080, which hits the root and then redirects. I then call stop() within a jsp page in the admin webapp.

Let me see if I can create a minimal test case in a minimal environment.

Chris

Show
Chris Cleveland added a comment - David, org.mortbay.thread.concurrent.ThreadPool should only have been referenced in the import statement. I wonder if the fact that it was on the classpath makes any difference? There were two webapps deployed: "root", which just contains a redirect to the "admin" webapp. There's nothing unusual in either. When the app starts, I open a browser to http://localhost:8080 , which hits the root and then redirects. I then call stop() within a jsp page in the admin webapp. Let me see if I can create a minimal test case in a minimal environment. Chris
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David Yu added a comment -

Waiting for the test case or the test webapp that u tested that against ... for it to be replicated.

Show
David Yu added a comment - Waiting for the test case or the test webapp that u tested that against ... for it to be replicated.
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Permalink
Chris Cleveland added a comment -

Simple test case added. To duplicate the issue, create this directory:

/temp/test/webapps/test

Copy index.jsp into it (attached)

Then run main() in JettyInvokerX.java (attached). You should see:

2007-08-10 16:06:47.269::INFO: Logging to STDERR via org.mortbay.log.StdErrLog
2007-08-10 16:06:47.300::INFO: jetty-6.1.5
2007-08-10 16:06:48.675::INFO: Started SelectChannelConnector@0.0.0.0:8080

in the console.

Open up a browser. Navigate to http://localhost:8080/test. Click "stop the server". The stack trace above should get dumped to the console.

The error occurs with both Firefox 1.5 and the most recent version of IE, so it's probably not a browser issue.

Show
Chris Cleveland added a comment - Simple test case added. To duplicate the issue, create this directory: /temp/test/webapps/test Copy index.jsp into it (attached) Then run main() in JettyInvokerX.java (attached). You should see: 2007-08-10 16:06:47.269::INFO: Logging to STDERR via org.mortbay.log.StdErrLog 2007-08-10 16:06:47.300::INFO: jetty-6.1.5 2007-08-10 16:06:48.675::INFO: Started SelectChannelConnector@0.0.0.0:8080 in the console. Open up a browser. Navigate to http://localhost:8080/test . Click "stop the server". The stack trace above should get dumped to the console. The error occurs with both Firefox 1.5 and the most recent version of IE, so it's probably not a browser issue.
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Chris Cleveland added a comment -

Also – forgot to mention – I'm running the test code inside Eclipse.

Show
Chris Cleveland added a comment - Also – forgot to mention – I'm running the test code inside Eclipse.
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David Yu added a comment -

Hi Chris,

Since you are also calling the server.stop from a thread coming from its own Threadpool, the call should be asynchronous.

First, configure your server to have a graceful shutdown:
server.setGracefulShutdown(3000); // 3 seconds

And on your stop() method, it should be called asynchronously so that the current running Thread(http request) will be returned to the ThreadPool before the server stops.

Take a look at the snippet below: (It has been tested)

static public void stop() throws Exception{
Thread thread = new Thread()
{
public void run()
{
try

{ server.stop(); }

catch(Exception e)

{ e.printStackTrace(); }

}
};
thread.setDaemon(true);
thread.start();

//if (server != null)

{ // server.stop(); //}

}

Show
David Yu added a comment - Hi Chris, Since you are also calling the server.stop from a thread coming from its own Threadpool, the call should be asynchronous. First, configure your server to have a graceful shutdown: server.setGracefulShutdown(3000); // 3 seconds And on your stop() method, it should be called asynchronously so that the current running Thread(http request) will be returned to the ThreadPool before the server stops. Take a look at the snippet below: (It has been tested) static public void stop() throws Exception{ Thread thread = new Thread() { public void run() { try { server.stop(); } catch(Exception e) { e.printStackTrace(); } } }; thread.setDaemon(true); thread.start(); //if (server != null) { // server.stop(); //} }
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David Yu added a comment -

not a bug.
This is why Jetty has a graceful shutdown feature .

Show
David Yu added a comment - not a bug. This is why Jetty has a graceful shutdown feature .
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Chris Cleveland added a comment -

Thanks. This makes sense. The proposed solution is not ideal, though, because:

1) It sets up a potential race condition

2) It doesn't throw any exceptions to the calling process, where they can be logged

3) It makes stopping the server non-deterministic, so you can't just press a button and then get feedback that the server has stopped.

I think we'll need something a little more complicated. I'll work on it.

Show
Chris Cleveland added a comment - Thanks. This makes sense. The proposed solution is not ideal, though, because: 1) It sets up a potential race condition 2) It doesn't throw any exceptions to the calling process, where they can be logged 3) It makes stopping the server non-deterministic, so you can't just press a button and then get feedback that the server has stopped. I think we'll need something a little more complicated. I'll work on it.

People

  • Assignee:
    David Yu
    Reporter:
    Chris Cleveland
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Dates

  • Created:
    Updated:
    Resolved: