[CONFIGURATION-390] AbstractHierarchicalFileConfiguration is not thread safe

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.6
• Component/s: File reloading
• Assignee: Unassigned
• Reporter: Emmanuel Bourg
• Created: 23/Jun/09 15:49
• Updated: 21/Oct/13 23:21

Description

AbstractHierarchicalFileConfiguration doesn't implement the same locking mechanism found in AbstractFileConfiguration. The consequence is that getting a property while the configuration is being reloaded by another thread can return an invalid result.

This can be demonstrated by changing testDeadlockWithReload() in TestCombinedConfiguration to use an XMLConfiguration instead of a PropertiesConfiguration.

Here is a reduced test case:

public void testConcurrentGetAndReload() throws Exception
{
    //final FileConfiguration config = new PropertiesConfiguration("test.properties");
    final FileConfiguration config = new XMLConfiguration("test.xml");
    config.setReloadingStrategy(new FileAlwaysReloadingStrategy());

    assertTrue("Property not found", config.getProperty("test.short") != null);

    new Thread()
    {
        public void run()
        {
            for (int i = 0; i < 1000; i++)
            {
                config.reload();
            }
        }
    }.start();
    
    for (int i = 0; i < 1000; i++)
    {
        assertTrue("Property not found", config.getProperty("test.short") != null); // failure here
    }
}

The test doesn't always fail. It does about 50% of the time.

Issue Links

• is related to: CONFIGURATION-344 Deadlock during refresh properties