DO NOT REPLY [Bug 17847] New: - MessageFormat usage in MessageResources.java

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http://nagoya.apache.org/bugzilla/show_bug.cgi?id=17847

MessageFormat usage in MessageResources.java

           Summary: MessageFormat usage in MessageResources.java
           Product: Struts
           Version: 1.1 RC1
          Platform: Other
        OS/Version: Other
            Status: NEW
          Severity: Minor
          Priority: Other
         Component: Utilities
        AssignedTo: struts-dev@jakarta.apache.org
        ReportedBy: ncoleman@leanlogistics.com


In profiling struts-el, I noticed a big lag in the standard taglib Resources 
class in that it calls MessageFormat.format rather than caching preparsed
formats.   The initialization of a MessageFormat is easily 75% of the time
spend while the call to format() is only 25%.   I entered a bug about this
last week but have seen no response.

This is why I was happy to see that the struts' MessageResources class
utilizes a hashtable to cache the formats.   However, in studying this I was
wondering about high contention among many threads for the same format. Would 
the lag actually increase if many threads had to wait for the same format?  For 
example, if MessageFormat.format() took 32ms and reusing a cached format took 
8ms and 10 threads tried to use the same format simultaneously, would this be 
slower since the 10th thread had to wait 10*8ms = 80ms.

Therefore, I proposed a simple pooling idea inside the hashtable and thought 
you may be interested if improving performance.  It looked like the following 
for the standard taglib Resources class.

    public static String getMessage(String name, Object[] a)
        throws MissingResourceException {

        // Retrieve pre-parsed format pool for message
        Stack formatPool = (Stack) formats.get(name);
        if (formatPool==null) {
            formatPool = new Stack();
            formats.put(name, formatPool);
        }

        // Retrieve format from pool or create a new one if pool
        // is empty
        MessageFormat messageFormat = null;
        try {
            messageFormat = (MessageFormat) formatPool.pop();
        }
        catch(EmptyStackException emptyx) {
            messageFormat = new MessageFormat(rb.getString(name));
        }

        // Generate formatted message
        String message = messageFormat.format(a);

        // Put parsed format back in pool for re-use by
        // another thread
        formatPool.push(messageFormat);

        return message;
    }


Note, the pooling was built upon the java Hashtable and Stack classes which are 
thread safe.

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