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Full Discussion: Multithreading in reading file
Top Forums Programming Multithreading in reading file Post 302576126 by Corona688 on Wednesday 23rd of November 2011 05:08:45 PM
Old 11-23-2011
Code:
$ cat getsecsal.c

#include <stdio.h>
#include <string.h>

int main(void)
{
        char buf[16384];
        char section[16384];

        while(fgets(buf, 16384, stdin))
        {
                char *substr;
                if(substr=strstr(buf,"<Section>"))
                {
                        substr += strlen("<Section>");
                        char *end=strstr(substr, "</ Section>");
                        if(end) (*end)='\0';
                        strcpy(section, substr);
                }
                else if(substr=strstr(buf,"<Salary>"))
                {
                        substr += strlen("<Salary>");
                        char *end=strstr(substr, "</Salary>");
                        if(end) (*end)='\0';

                        printf("%s~%s\n", section, substr);
                }
        }
}

$ gcc getsecsal.c
$ ls -lh data[12]
-rw-r--r-- 1 tyler users 1.7G Nov 23 15:57 data1
-rw-r--r-- 1 tyler users  208 Nov 23 15:57 data2
$ cat data2

<EMPLOYEE>
<RECORD id =XYZ >
<SSN>123</SSN>
<Section>dfdf</ Section>
<Salary>34343</Salary>
</RECORD>
<RECORD id =XZY >
< SSN >321</ SSN >
<Section>dfd</ Section>
<Salary>34343</Salary>
</RECORD>
</EMPLOYEE>

$ ./a.out < data2
dfdf~34343
dfd~34343

$ time ./a.out < data1 > /dev/null

real    0m46.661s
user    0m42.820s
sys     0m2.221s

$

1.7 gigabytes of data in 46.7 seconds is 37 megabytes per second -- the fastest speed my disk controller gets. I'd need a faster disk controller to do any better. More threads wouldn't do a thing.

If the tags in any of your records are actually different from what you posted, it won't work.
This User Gave Thanks to Corona688 For This Post:
arunkumar_mca
 

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LEARN ABOUT DEBIAN

graph::reader::xml

Graph::Reader::XML(3pm) 				User Contributed Perl Documentation				   Graph::Reader::XML(3pm)

NAME

       Graph::Reader::XML - class for reading a Graph instance from XML

SYNOPSIS

	 use Graph::Reader::XML;
	 use Graph;

	 $reader = Graph::Reader::XML->new();
	 $graph = $reader->read_graph('mygraph.xml');

DESCRIPTION

       Graph::Reader::XML is a perl class used to read a directed graph stored as XML, and return an instance of the Graph class.

       The XML format is designed to support the Graph classes: it can be used to represent a single graph with a collection of nodes, and edges
       between those nodes.  The graph, nodes, and edges can all have attributes specified,

       Graph::Reader::XML is a subclass of Graph::Reader, which defines the generic interface for Graph reader classes.

METHODS

   new()
       Constructor - generate a new reader instance.

	 $reader = Graph::Reader::XML->new();

       This doesn't take any arguments.

   read_graph()
       Read a graph from a file:

	 $graph = $reader->read_graph( $file );

       The $file argument can be either a filename or a filehandle of a previously opened file.

KNOWN BUGS

       Attribute values must be scalar. If they're not, well, you're on your own.

SEE ALSO

       Graph::Reader
	   The base class for Graph::Reader::XML.

       Graph::Writer::XML
	   Used to serialise a Graph instance as XML.

       Graph
	   Jarkko Hietaniemi's classes for representing directed graphs.

AUTHOR

       Neil Bowers <neil@bowers.com>

COPYRIGHT

       Copyright (c) 2001-2012, Neil Bowers. All rights reserved.  Copyright (c) 2001, Canon Research Centre Europe. All rights reserved.

       This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

perl v5.14.2							    2012-02-14						   Graph::Reader::XML(3pm)
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