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Re: [cross-project-issues-dev] Observation: Frequent UI freezes when working with files

The IResource/IWorkspace API is backed by a completely in-memory skeleton of your file system structure. So any time you can query the resource model instead of the file system, you will see orders of magnitude performance improvement over direct java.io.File access. The IResource API (and EFS) encourage a batch-style interaction for the rare thing that is not in memory. For example IResource#getResourceAttributes or IFileStore#fetchInfo  returns a struct of all the attributes in a single native call, which is vastly more efficient than doing many calls such as if (file.exists() && file.isFile() && file.canRead()) {... }.

For the IResource API and much of the rest of the platform API, the best indicator is whether there is an IProgressMonitor in the API method. If the method takes a progress monitor, you probably don't want to call it from the UI thread. If there is no progress monitor, then for the most part you are ok. There are a few embarrassing exceptions to this (e.g.,, Job#join), but it's a useful rule of thumb.

John




From:        Lars Vogel <lars.vogel@xxxxxxxxx>
To:        Cross project issues <cross-project-issues-dev@xxxxxxxxxxx>
Date:        12/11/2014 01:38 PM
Subject:        Re: [cross-project-issues-dev] Observation: Frequent UI freezes when working with files
Sent by:        cross-project-issues-dev-bounces@xxxxxxxxxxx




I would guess that java.nio.file.Files.exists() [1] improves this access performance. Do you see these freezes cause by org.eclipse.core.resources.IResources or by directly using the Java File API?

[1] http://docs.oracle.com/javase/7/docs/api/java/nio/file/Files.html#exists(java.nio.file.Path,%20java.nio.file.LinkOption...))

2014-12-10 14:53 GMT+01:00 Marcel Bruch <marcel.bruch@xxxxxxxxxxxxxx>:
Hi,

I just want to share an insight I got from reviewing several ui freezes. One common cause for UI freezes are operations that touch the filesystem. For instance, File.isFile, File.lastModified, or WinNTFileSystem.getBooleanAttributes seem to be very expensive. From what I read on the internet it seems that some of these methods (e.g. getAttributes) may even take up to several seconds to return on windows systems.


This has been discussed elsewhere in the internet [1] and seems to be a long-standing issue in Java.



With this mail Iâd like to make you aware of this (in case you did not know this before) and would like to encourage you to actually not execute file operations in the ui thread. We may also consider doing some kind of caching but such a discussion would by far be over my knowledge, and thus, should be left to discuss with the platform team.

For now, I think we would benefit very much if every project that accesses files/resources would review their code and think about refactoring some part of the FileSystem work (even if itâs only checking a fileâs attributes) into background processes.

Best,
Marcel


[1]
http://stackoverflow.com/questions/20546676/webstart-winntfilesystem-getbooleanattributes-performance


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