Debugging Filesystem Sync Problems

Problem Description

After doing some modifications to a file or directory outside an IDE and switching back, the changes are not visible in a Project View tree and/or in an editor. Important note: a change to a file should result in a different length or a modification timestamp.

Basic Checks

First, please make sure that Settings | Appearance & Behavior | System Settings | Synchronize external changes ... option is enabled.

Syncing changes may take some notable time. Make sure there is no spinning "Synchronizing ..." indicator in the lower left corner of the IDE window before reporting the problem.

Last, please check that the issue isn't caused by UI. For example, if a new file doesn't appear in the Project View tree, check whether collapsing/expanding a parent node reveals it.

Reporting

Locate the log directory (Help | Show Logs ...).

Shut down the IDE and delete everything from the log directory.

Start the IDE, open a project, and add the following lines to Help | Diagnostic Tools | Debug Log Settings:

#com.intellij.openapi.vfs.impl.local.NativeFileWatcherImpl:trace
#com.intellij.openapi.vfs.newvfs.RefreshSession:trace
#com.intellij.openapi.vfs.newvfs.persistent.RefreshWorker:trace

Switch from the IDE and make a change to a file or a directory in the project (e.g. run echo foo >> some_file); note a time.

Switch back to the IDE, wait until syncing is finished, verify that the problem is reproduced (i.e. the IDE doesn't see the change), then archive all idea.log* files.

When reporting an issue, provide collected logs, the time of the change, a path to the file or directory that was modified, and the nature of a change.

When done, do not forget to clear the debug log settings - otherwise, excessive logging may slow down the IDE.