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POstl map simultaneous write sample code
 

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    <p>I want to simulate the abnormal behavior of stl map in simultaneous write condition. Here I am using a single map and simultaneously inserting data from multiple threads. As we are using only one map object, hence it should not allow. Please go through the following sample code</p> <pre><code> #include &lt;iostream&gt; #include &lt;map&gt; #include &lt;iterator&gt; #include &lt;algorithm&gt; extern "C" { #include &lt;pthread.h&gt; #include &lt;string.h&gt; #include &lt;stdlib.h&gt; } using namespace std; //functor to print map struct PrintMp { void operator()(pair&lt;int,int&gt; pr) { cout&lt;&lt;pr.first&lt;&lt;" =&gt; "&lt;&lt;pr.second&lt;&lt;endl; } }; //thread 1 //inserts continuous no from 0 to 4999 void* ins_th1(void *arg) { map&lt;int, int&gt; *mp = static_cast&lt;map&lt;int, int&gt;* &gt;(arg); for(int i =0 ; i&lt;5000; i++) mp-&gt;insert(pair&lt;int,int&gt;(i, i+1000)); return NULL; } //thread 1 //inserts continuous no from 0 to 4999 void* ins_th2(void *arg) { map&lt;int, int&gt; *mp = static_cast&lt;map&lt;int,int&gt;* &gt;(arg); for(int i=5000; i&lt;10000; i++) mp-&gt;insert(pair&lt;int, int&gt;(i, i+2000)); return NULL; } int main() { typedef map&lt;int, int&gt; IntMapType; IntMapType mp; PrintMp MpPrintObj; int rc; pthread_t th1, th2; //thread 1 creation rc = pthread_create(&amp;th1, NULL, ins_th1, static_cast&lt;void*&gt;(&amp;mp)); if ( rc != 0) { cerr&lt;&lt;strerror(rc)&lt;&lt;"in thread1"&lt;&lt;endl; exit(EXIT_FAILURE); } //thread 2 creation rc = pthread_create(&amp;th2, NULL, ins_th2, static_cast&lt;void*&gt;(&amp;mp)); if(rc!=0) { cerr&lt;&lt;strerror(rc)&lt;&lt;"in thread2"&lt;&lt;endl; exit(EXIT_FAILURE); } //lets wait for the thread to finish rc = pthread_join(th1, NULL); if ( rc != 0) { cerr&lt;&lt;strerror(rc)&lt;&lt;"join failure for thread1"&lt;&lt;endl; exit(EXIT_FAILURE); } rc = pthread_join(th2, NULL); if ( rc != 0) { cerr&lt;&lt;strerror(rc)&lt;&lt;"join failure for thread2"&lt;&lt;endl; exit(EXIT_FAILURE); } cout&lt;&lt;"Map data"&lt;&lt;endl; //now print it for_each(mp.begin(), mp.end(), MpPrintObj); cout&lt;&lt;endl; return 0; } </code></pre> <p>But it doesn't work. Can anyone suggest me some approach ?</p>
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    1. USasit_dhal
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    1. COWhat do you mean it doesn't work? What happens?
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      1. USanio
    2. COIt _doesn't_ work, or it _did_ work and you didn't expect it to?
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      1. USChad
    3. COI expected it not to show proper output as stl map is not thread safe. But its showing everything proper.
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