Deadlock! while stopping Geronimo server from within Eclipse
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Key: GERONIMODEVTOOLS-178
URL: https://issues.apache.org/jira/browse/GERONIMODEVTOOLS-178
Project: Geronimo-Devtools
Issue Type: Bug
Components: eclipse-plugin
Affects Versions: 1.2.0, 1.2.1, 2.0
Reporter: Shiva Kumar H R
An interesting deadlock scenario!
Here are the steps to reproduce:
1. From within Eclipse start Geronimo server (say 2.0)
2. Deploy attached WAR
3. Access deployed servlet with url "http://localhost:8080/TestDeadlock/Test";
4. From within Eclipse invoke "Stop" server
You will see that Stop never returns and Eclipse freezes to respond.
5. Manually kill server process and Eclipse will resume.
Here is what is happening:
1. When user invokes "Stop" on Geronimo server from within Eclipse, Geronimo
Eclipse Plug-in invokes stopKernel() in the main Eclipse thread itself.
(org.apache.geronimo.st.core.GeronimoServerBehaviourDelegate.java::stop())
2. Server receives the shutdown call, and invokes the deployed WAR's
"servlet.destroy" method, which in turn opens a big text file and starts
printing the contents to standard output.
3. All the output buffers overflow because the main thread is the one that
should push them to the console view at the end but it is blocked.
4. All the print operations on the server side are blocked waiting for somebody
to read the output buffer. The shutdown call will never return.
5. The main Eclipse thread will never print the messages because it waits for
the shutdown call to return.
Here is one solution thought of:
The Geronimo Eclipse plug-in should make the shutdown call in a worker thread
not in the main Eclipse thread. In this case the main thread will be able to
display all the messages triggered by the shutdown call and everything will
work just fine. Attached patch implements this.
Please see this also:
http://www.eclipse.org/webtools/wst/api/org/eclipse/wst/server/core/model/ServerBehaviourDelegate.html#stop(boolean)
It recommends that the plug-in should return from the
"ServerBehaviourDelegate.stop()" method quickly and use the server listener to
notify shutdown progress.
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