A question about method dispose() in Aspose. Email for Java

Aspose.Email Product Family
1

I looked at the introduction to method dispose() in Aspose.Email for Java, but I’m not sure how I should use it to flush memory. The below is my code:

            PersonalStorage personalStorage = PersonalStorage.create(currentPstFilePath, FileFormatVersion.Unicode);
            FolderInfo inboxFolder = personalStorage.getRootFolder().addSubFolder("Inbox");
            for (Path emlFile : fileSet) {
                try {
                    MailMessage eml = MailMessage.load(emlFile.toString());
                    inboxFolder.addMessage(MapiMessage.fromMailMessage(eml));
                    eml.dispose();
                      } catch (Exception e) {
                           log.error("Error processing file: %s,%s".formatted(emlFile, e.getMessage()));
                           log.error(Arrays.toString(e.getStackTrace()));
                }
}
personalStorage.close();

In the above for-loop, after it adds MailMessage eml to inboxFolder it call dispose() for this eml. Later, it throws NPE exception but it does not affect the EML to PST conversion. I still see the size of PST file increasing. Also, I don’t see any memory release on JVM heap. So I’m curious about the role of dispose and how to use it correctly for MailMessage and PersonalStorage.

2

@Superpotatoo

The dispose() method in Aspose.Email for Java is designed to free, release, or reset unmanaged resources associated with an object. In your case, you are using it on the MailMessage object after adding it to the inboxFolder. This is a good practice to help manage memory, especially when dealing with large numbers of email messages.

However, it’s important to note that calling dispose() on an object does not immediately free up memory in the Java Virtual Machine (JVM) heap. Instead, it marks the resources used by that object for garbage collection. The actual memory release will occur when the garbage collector runs, which is not guaranteed to happen immediately after dispose() is called.

In your code, you are correctly calling eml.dispose() after adding the message to the folder. If you are encountering a NullPointerException (NPE) after this call, it may be due to trying to access the eml object after it has been disposed. Ensure that you do not use the eml object after calling dispose() on it.

Here’s a brief overview of how to use dispose() correctly in your context:

  1. Create and Use the Object: Load the MailMessage and use it as needed.
  2. Add to Folder: After processing, add the MailMessage to the inboxFolder.
  3. Dispose: Call dispose() on the MailMessage to free resources.
  4. Avoid Further Use: Do not attempt to access the MailMessage after calling dispose().

Here’s a simplified version of your loop with comments:

for (Path emlFile : fileSet) {
    try {
        // Load the MailMessage from the EML file
        MailMessage eml = MailMessage.load(emlFile.toString());
        
        // Add the message to the inbox folder
        inboxFolder.addMessage(MapiMessage.fromMailMessage(eml));
        
        // Dispose of the MailMessage to free resources
        eml.dispose();
        
    } catch (Exception e) {
        log.error("Error processing file: %s,%s".formatted(emlFile, e.getMessage()));
        log.error(Arrays.toString(e.getStackTrace()));
    }
}

If you continue to experience issues with memory not being released, consider monitoring the JVM’s memory usage and garbage collection behavior. You can also explore using profiling tools to analyze memory usage in your application.

For more detailed information about the dispose() method and its usage, you can refer to the Aspose.Email for Java API documentation here.

If you have further questions or need additional assistance, feel free to ask!

3

How about dispose() for PersonalStorage? In what cases should I use dispose() instead of close().

4

I just checked the code, and I confirmed that it is not accessing MailMessage after calling dispose() .

5

Hello @Superpotatoo,

To reproduce the NPE you’re encountering, could you please share:

  • the full code example that leads to the exception
  • the input files (or a minimal set that causes the issue)
  • the stack trace of the exception

This will help us investigate whether the issue is related to the dispose() or close() methods, or if it’s caused by something else in the code or data.

Thank you.