[jfreechart-dev] [ jfreechart-Bugs-1536558 ] RegularTimePeriond not thread safe

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Bugs item #1536558, was opened at 2006-08-08 10:10
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Category: General
Group: 1.0.x
Status: Open
Resolution: None
Priority: 5
Submitted By: Colin Crist (colincrist)
Assigned to: Nobody/Anonymous (nobody)
Summary: RegularTimePeriond not thread safe

Initial Comment:

RegularTimePeriod.java (1.6.2.1) has a static Calendar.

I have seem this cause problems if if data is placed
into two TimeSeries concurrently - Dates can get
created with incorrect values and other weirdness
caused by Calendar not being thread safe.

I have worked around the problem by changing the
Calendar to being a ThreadLocal (I guess
Calendar.getInstance returns a new Calendar each time...)

 public static final ThreadLocal WORKING_CALENDAR_TL =
new ThreadLocal () ;
    
    public static Calendar getWorkingCalendar()
    {
    	if (WORKING_CALENDAR_TL.get() == null)
    	{
    	
WORKING_CALENDAR_TL.set(Calendar.getInstance(DEFAULT_TIME_ZONE))
;
    	}
    	
    	return (Calendar) WORKING_CALENDAR_TL.get() ;
    }

Access to the calendar in the rest of the class is now
via this getter. It works fine except you will leak
Calendars when threads terminate. A better solution may
be to place the Calendars in an LRUMap with some
reasonable fixed upper limit.

Regards, Colin.

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