SECTION 72 in Java

Encode Data Matrix ECC200 in Java SECTION 72
SECTION 72
Encoding ECC200 In Java
Using Barcode creator for Java Control to generate, create ECC200 image in Java applications.
TIMING AND PROFILING
Printing Barcode In Java
Using Barcode encoder for Java Control to generate, create barcode image in Java applications.
Exercise 7-1 A table that maps a single character to the set of patterns that begin
Reading Barcode In Java
Using Barcode recognizer for Java Control to read, scan read, scan image in Java applications.
with that character gives an order of magnitude improvement Implement a version of
Print Data Matrix 2d Barcode In Visual C#
Using Barcode maker for .NET Control to generate, create Data Matrix image in Visual Studio .NET applications.
i sspam that uses two characters as the index How much improvement does that lead to Thcsc arc simple special cases of a data structure called a trie Most such data
DataMatrix Encoder In .NET
Using Barcode creator for ASP.NET Control to generate, create DataMatrix image in ASP.NET applications.
structures are based on trading space for time
Data Matrix ECC200 Drawer In VS .NET
Using Barcode drawer for VS .NET Control to generate, create Data Matrix 2d barcode image in VS .NET applications.
72 Timing and Profiling
ECC200 Encoder In VB.NET
Using Barcode creation for VS .NET Control to generate, create Data Matrix 2d barcode image in VS .NET applications.
Automate timing measurements Most systems have a command to measure how long a program takes On Unix the command is called time:
Barcode Printer In Java
Using Barcode printer for Java Control to generate, create barcode image in Java applications.
% time slowprogram
Draw USS Code 39 In Java
Using Barcode creator for Java Control to generate, create Code 39 Extended image in Java applications.
real user
Code 128 Maker In Java
Using Barcode maker for Java Control to generate, create Code 128 Code Set C image in Java applications.
70 62 01
Drawing EAN128 In Java
Using Barcode generator for Java Control to generate, create GTIN - 128 image in Java applications.
This runs the command and reports three numbers, all in seconds: "real" time, the elapsed time for the program to complete; "user" CPU time time spent executing the user's program; and "system" CPU time, time spent within the operating system on the program's behalf If your system has a similar command, use it; the numbers will be more informative, reliable, and easier to track than time measured with a stopwatch And keep good notes As you work on the program, making modifications and measurements, you will accumulate a lot of data that can become confusing a day or two later (Which version was it that ran 20% faster ) Many of the techniques we discussed in the chapter on testing can be adapted for measuring and improving performance Use the machine to run and measure your test suites and, most inlportant, use regression testing to make sure your modifications don't break the program If your system doesn't have a time command, or if you're timing a function in isolation, it's easy to construct a timing scaffold analogous to a testing scaffold C and C++ provide a standard routine, clock, that reports how much CPU time the program has consumed so far It can be called before and after a function to measure CPU usage: #i ncl ude <time h> #include < s t d io h>
Painting Bar Code In Java
Using Barcode encoder for Java Control to generate, create bar code image in Java applications.
clock-t before; doubl e elapsed; before = clock(); long-runni ng-function0 ; elapsed = clock() - before; p r i n t f ( " f u n c t i o n used %3f seconds\nN, e l apsed/CLOCKS-PER-SEC) ;
ISSN - 13 Drawer In Java
Using Barcode printer for Java Control to generate, create ISSN - 10 image in Java applications.
PERFORMANCE
Read USS Code 128 In VS .NET
Using Barcode scanner for Visual Studio .NET Control to read, scan read, scan image in .NET framework applications.
The scaling term, CLOCKSPERSEC, records the resolution of the timer as reported by clock If the function takes only a small fraction of a second, run it in a loop but be sure to compensate for loop overhead if that is significant: before = clock(); f o r ( i = 0 ; i < 1000; i++) short- runni ng-function() ; elapsed = (clock()-before)/(double)i
Bar Code Printer In VB.NET
Using Barcode encoder for .NET framework Control to generate, create barcode image in .NET applications.
CPU time:
Bar Code Reader In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
In Java, functions in the Date class give wall clock time, which is an approximation to Date before = new Date(); long-runni ng-function() ; Date a f t e r = new Date(); long elapsed = a f t e r g e t T i m e 0 - beforegetTime(); The return value of getTime is in milliseconds
Drawing DataMatrix In Visual C#.NET
Using Barcode encoder for .NET framework Control to generate, create Data Matrix image in .NET framework applications.
Use a profler Besides a reliable timing method, the most important tool for performance analysis is a system for generating profiles A prqfile is a measurement of where a program spends its time Some profiles list each function, the number of times it is called, and the fraction of execution time it consumes Others show counts of how many times each statement was executed Statements that are executed frequently contribute more to run-time, while statements that are never executed may indicate useless code or code that is not being tested adequately Profiling is an effective tool for finding hot spots in a program, the functions or sections of code that consume most of the computing time Profiles should be interpreted with care, however Given the sophistication of compilers and the complexity of caching and memory effects as well as the fact that profiling a program affects its performance, the statistics in a profile can be only approximate In the 1971 paper that introduced the term profiling, Don Knuth wrote that "less than 4 per cent of a program generally accounts for more than half of its running time" This indicates that the way to use profiling is to identify the critical timeconsuming parts of the program, improve them to the degree possible, and then measure again to see if a new hot spot has surfaced Eventually, often after only one or two iterations there is no obvious hot spot left Profiling is usually enabled with a special compiler flag or option The program is run, and then an analysis tool shows the results On Unix, the flag is usually -p and the tool is called prof:
Printing Barcode In VS .NET
Using Barcode printer for ASP.NET Control to generate, create barcode image in ASP.NET applications.
Code-39 Generator In VB.NET
Using Barcode encoder for Visual Studio .NET Control to generate, create Code 39 image in .NET framework applications.