在NetBeans IDE中运行Shutdown Hook

Question

I'm developing an application that will run as a service. I have added a shutdown hook to the program to do some file cleanup. When I install the program as a service (on Linux as a daemon or as a Windows service) the shutdown hook executes correctly. However, when running in the IDE the shutdown hook is never executed. Is there a way to stop the running process in the IDE and have the shutdown hook execute?

Thanks, Pablo

Answer 1

Unfortunately there is no way to do this within the current Netbeans system,since the kill methods for both types of app testing (Debug and Normal) both, well kill the process, giving it no chance to cleanup. Depending on the architecture of your app you may be able to add a System.exit(0) call, but other than that you are stuck with opening it up in the console.

Answer 2

I disagree. A sigkill in unix or terminate process in windows by definition will kill the running process without giving any ability for the application to catch these events. This is necessary to terminate an unresponsive process. These signals should only be used when a process does not respond to a siginit (ctrl c) or a sigterm or end task in windows. NetBeans seems to be sending a sigkill rather than siginit or sigterm. As far as I'm concerned this is bad practice.

There should be a secondary option to kill the process however the primary end process button should be to send siginit or sigterm. Applications should anticipate the user hitting ctrl c or end task on their application and as a best effort cleanly close files/sockets and save persistent/state data. An application should not anticipate a sigkill or terminate process but rather be developed in such a way that a sigkill or terminate process are not necessary.

By NetBeans using these methods as the only means to terminate the application from the IDE is erroneous.

Answer 3

Nope. Don't cleanup your program using shutdown hooks. From the docs ...

In rare circumstances the virtual machine may abort, that is, stop running without shutting down cleanly. This occurs when the virtual machine is terminated externally, for example with the SIGKILL signal on Unix or the TerminateProcess call on Microsoft Windows. The virtual machine may also abort if a native method goes awry by, for example, corrupting internal data structures or attempting to access nonexistent memory. If the virtual machine aborts then no guarantee can be made about whether or not any shutdown hooks will be run.

When the contract says that there is no guarantee that your shutdown hooks will always be called, it is not advisable to use them for critical operations.