Java deleteOnExit and addShutdownHook - what comes first?

Question

I have several temporary files that I call deleteOnExit(). I also have an executable file that I register in addShutdownHook()to run on a call System.exit.

Is there any guarantee that temporary files will still be available when my shutdown hook is launched?

Answer 1

When we look at the underlying implementations, both are dealing with Shutdown-Hook.

1. When we are dealing with addShutdownHook (ApplicationShutdownHooks), we have a piece of code, as shown below in our code.

   Runtime.getRuntime().addShutdownHook(new Thread() {
         public void run() { 
               <<---Do the Implementations here--->>
         }
       });
   

Java ApplicationShutdownHooks , , Runtime, http://www.docjar.com/html/api/java/lang/Runtime.java.html.

class ApplicationShutdownHooks {
    /* The set of registered hooks */
    private static IdentityHashMap<Thread, Thread> hooks;
    static {
        try {
            Shutdown.add(1 /* shutdown hook invocation order */,
                false /* not registered if shutdown in progress */,
                new Runnable() {
                    public void run() {
                        runHooks();
                    }
                }
            );

2. , File.deleteOnExit(), Java , .

           // DeleteOnExitHook must be the last shutdown hook to be invoked.
           // Application shutdown hooks may add the first file to the
           // delete on exit list and cause the DeleteOnExitHook to be
           // registered during shutdown in progress. So set the
           // registerShutdownInProgress parameter to true.
           sun.misc.SharedSecrets.getJavaLangAccess()
               .registerShutdownHook(2 /* Shutdown hook invocation order */,
                   true /* register even if shutdown in progress */,
                   new Runnable() {
                       public void run() {
                          runHooks();
                       }
                   }
           );
   

   . , , JavaSourceCode, : http://hg.openjdk.java.net/icedtea/jdk7/jdk/file/10672183380a/src/share/classes/java/io/DeleteOnExitHook.java http://hg.openjdk.java.net/icedtea/jdk7/jdk/file/10672183380a/src/share/classes/java/io/File.java

Shutdown Hook , . , Shutdown Hooks . , :

ApplicationShutdownHooks: https://docs.oracle.com/javase/7/docs/api/java/lang/Runtime.html#addShutdownHook (java.lang.Thread)

deleteOnExit: https://docs.oracle.com/javase/7/docs/api/java/io/File.html#deleteOnExit()

, ApplicationShutdownHooks, deleteOnExit(), deleteOnExit() , JVM.

. , deleteOnExit() , , , , :

Path path = FileSystems.getDefault.getPath(".");
File asFile = path.toFile();
asFile.deleteOnExit();