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    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

    12 <concept id="GUID-C7B748CF-D080-5448-98AF-1634D821E713" xml:lang="en"><title> SMP

    13 Example</title><shortdesc>This example demonstrates symmetric multiprocessing using multiple

    14 threads. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    15 <p>This example shows the differences between code running in a unicore environment

    16 and in a multiprocessor environment.</p>

    17 <section id="GUID-7AC2BE12-4F01-4140-8379-672475DE7681"><title>Download</title> <p>Click on the following link to download

    18 the example: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/zips/guid-577596d8-76a2-4a41-aa0f-deefe5638e23.zip" scope="external">SmpExample.zip</xref></p><p>Click: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/guid-577596d8-76a2-4a41-aa0f-deefe5638e23.html" scope="peer">browse</xref> to view the example code. </p> </section>

    19 <section id="GUID-7A70847E-40A2-4267-9BD4-36F88F48C84A"><title>Class summary</title><ul>

    20 <li><p><xref href="GUID-B0E661BC-4058-3256-B9C3-5A4FD52F6DE5.dita"><apiname>RThread</apiname></xref> - A handle to a thread.</p></li>

    21 <li><p><xref href="GUID-F4A68645-2265-307F-B951-8295827E000B.dita"><apiname>RDbStoreDatabase</apiname></xref> - DBMS Store database implementation</p></li>

    22 </ul></section>

    23 <section id="GUID-BE13F08D-09FD-41DF-9210-D46EBECADA69"><title>Design and implementation</title> <p>The example creates two

    24 databases named DBforSMP1.db and DBforSMP2.db and three threads: </p> <ul>

    25 <li id="GUID-F4EE1C84-FE30-5C99-872B-1881D852CAEA"><p> <codeph>WriterThread1</codeph>:

    26 It creates the DBforSMP1.db database and writes integers to it. The thread

    27 has the lowest priority amongst all the threads. </p> </li>

    28 <li id="GUID-7B2D0419-E069-59FA-A6CE-70EBC203F656"><p> <codeph>WriterThread2</codeph>:

    29 It creates the DBforSMP2.db database and writes some integers to it. The thread

    30 has highest priority amongst all the threads. </p> </li>

    31 <li id="GUID-7C9584F2-E6C8-5A02-B4C2-4845CF4BAA36"><p> <codeph>ReaderThread</codeph>:

    32 It reads the two databases and prints the output to the console. It has normal

    33 priority. </p> </li>

    34 </ul> <p>In a unicore enviroment, the threads are executed according to their

    35 priorities. This means first <codeph> WriterThread2</codeph>, then <codeph>ReaderThread</codeph> and

    36 finally <codeph>WriterThread1</codeph> is executed. Hence <codeph>ReaderThead</codeph> can

    37 only print the contents of the DBforSMP2.db in the console because DBforSMP1

    38 is empty. in an SMP environment, threads run simultaneously and <codeph>ReaderThread</codeph> can

    39 print the contents of both the databases. </p> </section>

    40 <section id="GUID-3686F166-C4DD-4269-9B9C-F0027F53547E"><title>Building and configuring</title> <p>To build the example: </p> <ul>

    41 <li id="GUID-037442C7-2436-5152-9A3E-9DC0B4283A9C-GENID-1-7-1-14-1-1-8-1-4-1-25-1-30-1-3-5-3-1"><p>The example builds an

    42 executable called <filepath>smpexample.exe</filepath> in the standard location. </p> </li>

    43 <li id="GUID-B7C849B9-0885-5253-A78B-71854F86D772-GENID-1-7-1-14-1-1-8-1-4-1-25-1-30-1-3-5-3-2"><p>You can build the example

    44 from your IDE or the command line. </p> <p>If you use an IDE, import the <filepath>bld.inf</filepath> file

    45 of the example into your IDE, and use the build command of the IDE. </p> <p>If

    46 you use the command line, open a command prompt, and set the current directory

    47 to the source code directory of the example. You can then build the example

    48 with the SBSv1 build tools with the following commands: </p> <p><userinput>bldmake

    49 bldfiles</userinput> </p> <p><userinput>abld build</userinput> </p> <p><xref href="GUID-793A5EF9-CC16-5EEB-9011-6431EA76EB15.dita">How to use bldmake</xref> and <xref href="GUID-B6B54E07-3B34-5D5C-8815-93383FA8FB4B.dita">How to use abld</xref> describe

    50 how to use the SBSv1 build tools. </p> </li>

    51 </ul> </section>

    52 <section id="GUID-F773B722-7612-4BAF-99CB-84E39CE10C40"><title>Running the example</title> <p>To test the example in an SMP

    53 environment, add <codeph>crazyscheduling on</codeph>in the <filepath>epoc32\data\epoc.ini</filepath> file.

    54 This emulates SMP behaviour in the techview emulator. Execute the example

    55 in both unicore and multiprocessor environment and see the difference. Run

    56 the example following the instructions provided in the console. </p> </section>

    57 </conbody></concept>