380005 - Date to String conversion code in NativeDate class is not thread-safe

Status: RESOLVED FIXED

(Rhino Graveyard :: Core, defect)

Description

[Gary Xue]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.8.0.11) Gecko/20070312 Firefox/1.5.0.11
Build Identifier: 1.6R1

Class org.mozilla.javascript.NativeDate class uses static java.text.DateFormat instances (members: timeZoneFormatter,localeDateTimeFormatter,localeDateFormatter, localeTimeFormatter) to convert date/time values to string. However DateFormat instances are not thread-safe (check JDK documentation). This results in occasional runtime exceptions when expressions containing date->string conversion are evaluated concurrently.

See Steps to Reproduce for sample code that demonstrates this problem. This code evaluates an expression 
   "Date:" + date_var
in 20 concurrent threads. The test code occasionally gives an ArrayIndexOutOfBoundsException.

Reproducible: Sometimes

Steps to Reproduce:
1.Run the following test code, preferrably on a multi-CPU machine. I've reliably reproduced this on a dual-Intel P4 2.8GHZ machine running Windows 2003 Server, against JRE version 1.5.0_07

2. The program occasionally dumps an exception. See Actual Results for stack. This happens about 1 out of 5 runs in my test. 

---- Test Code  ----

import java.util.Random;
import org.mozilla.javascript.Context;
import org.mozilla.javascript.Scriptable;

public class DateConversionTest
{
	
	public static void main(String[] args) throws Exception
	{
		// Run 10 threads
		for ( int i = 0; i < 20; i++ )
		{
			Thread t = new TestThread();
			t.start();
		}
	}
	
	static class TestThread extends Thread
	{
        public void run() 
        {
        	Context cx;
        	Scriptable scope;
    		cx = Context.enter();
    		scope = cx.initStandardObjects();

    		Random rand = new Random();

    		for (int i = 0; i < 1000; i++)
    		{
        		int year = rand.nextInt(10) + 1990;
        		int month = rand.nextInt(12) + 1;
        		int day = rand.nextInt(28) + 1;
        		int hour = rand.nextInt(24);
        		int minute = rand.nextInt(60);
        		int sec = rand.nextInt(60);
        		
            	String expr = "\"Date: \" + new Date( " + 
            		year + "," + month + "," + day + "," + hour + "," + minute + "," + sec + ")"; 
        		cx.evaluateString( scope, expr, "", 1, null );
    		}
    		
    		Context.exit();
        }		
	}
	
}

Actual Results:  
Exception: 

Exception in thread "Thread-14" java.lang.ArrayIndexOutOfBoundsException: 22
        at sun.util.calendar.BaseCalendar.getCalendarDateFromFixedDate(Unknown Source)
        at java.util.GregorianCalendar.computeFields(Unknown Source)
        at java.util.GregorianCalendar.computeFields(Unknown Source)
        at java.util.Calendar.setTimeInMillis(Unknown Source)
        at java.util.Calendar.setTime(Unknown Source)
        at java.text.SimpleDateFormat.format(Unknown Source)
        at java.text.SimpleDateFormat.format(Unknown Source)
        at java.text.DateFormat.format(Unknown Source)
        at org.mozilla.javascript.NativeDate.date_format(NativeDate.java:1054)
        at org.mozilla.javascript.NativeDate.execIdCall(NativeDate.java:201)
        at org.mozilla.javascript.IdFunctionObject.call(IdFunctionObject.java:121)
        at org.mozilla.javascript.ScriptableObject.getDefaultValue(ScriptableObject.java:577)
        at org.mozilla.javascript.NativeDate.getDefaultValue(NativeDate.java:84)
        at org.mozilla.javascript.ScriptRuntime.add(ScriptRuntime.java:2290)
        at org.mozilla.javascript.gen.c2708._c0(:1)
        at org.mozilla.javascript.gen.c2708.call()
        at org.mozilla.javascript.ContextFactory.doTopCall(ContextFactory.java:304)
        at org.mozilla.javascript.ScriptRuntime.doTopCall(ScriptRuntime.java:2769)
        at org.mozilla.javascript.gen.c2708.call()
        at org.mozilla.javascript.gen.c2708.exec()
        at org.mozilla.javascript.Context.evaluateString(Context.java:1220)
        at DateConversionTest$TestThread.run(DateConversionTest.java:61)


Expected Results:  
No exception

Use an instance of DateFormat per thread. Or synchronize code that accesses the static DateFormat instances.

Comment 1

[Norris Boyd]

Fixed: 

Checking in NativeDate.java;
/cvsroot/mozilla/js/rhino/src/org/mozilla/javascript/NativeDate.java,v  <--  NativeDate.java
new revision: 1.65.2.1; previous revision: 1.65
done

I just synchronized access to the static DateFormat instances. 

Comment 2

[Gary Xue]

Norris - thanks for the fix. Did this fix make it into the 1.6R6 release? Thanks, Gary