Hi, Phil,<br><br>Valgrind user manual give no more information than &quot; Applications that use the Boost.Thread library should run fine under DRD.&quot; I ran your code using DRD tool  of valgrind and got race warnings too.<br>
<br>I then ran the following thread_group.cpp code distributed with boost_1_42, debugged it with valgrind --tool=drd, and it gave race warnings (more errors than your code) too:<br><br>int count = 0;<br>boost::mutex mutex;<br>
<br>void increment_count()<br>{<br>    boost::mutex::scoped_lock lock(mutex);<br>    std::cout &lt;&lt; &quot;count = &quot; &lt;&lt; ++count &lt;&lt; std::endl;<br>}<br><br>int main(int argc, char* argv[])<br>{<br>    boost::thread_group threads;<br>
    for (int i = 0; i &lt; 10; ++i)<br>        threads.create_thread(&amp;increment_count);<br>    threads.join_all();<br>}<br><br>This suggests that valgrind might give false race warnings for boost thread code. Although I am not 100% sure of it. BTW, what other debugging tools are available to us for debugging boost threaded code?<br>
<br>Robert<br><br><div class="gmail_quote"><br>On Wed, Nov 24, 2010 at 11:05 AM, Kraus Philipp <span dir="ltr">&lt;<a href="mailto:philipp.kraus@flashpixx.de">philipp.kraus@flashpixx.de</a>&gt;</span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div style="word-wrap: break-word;">Hello,<div><br></div><div>I have written this little example:</div><div><br></div><div><div style="margin: 0px; color: rgb(63, 110, 116);">boost<span style="color: rgb(0, 0, 0);">::</span>mutex<span style="color: rgb(0, 0, 0);"> </span>mutex<span style="color: rgb(0, 0, 0);">; </span></div>
<div style="margin: 0px;"><span style="color: rgb(170, 13, 145);"><br></span></div><div style="margin: 0px;"><span style="color: rgb(170, 13, 145);">void</span> thread() </div><div style="margin: 0px;">{ </div><div style="margin: 0px;">
    <span style="color: rgb(170, 13, 145);">for</span> (<span style="color: rgb(170, 13, 145);">int</span> <span style="color: rgb(63, 110, 116);">i</span> = <span style="color: rgb(28, 0, 207);">0</span>; <span style="color: rgb(63, 110, 116);">i</span> &lt; <span style="color: rgb(28, 0, 207);">5</span>; ++<span style="color: rgb(63, 110, 116);">i</span>) </div>
<div style="margin: 0px;">    { </div><div style="margin: 0px;">        <span style="color: rgb(63, 110, 116);">boost</span>::this_thread::sleep(<span style="color: rgb(63, 110, 116);">boost</span>::posix_time::seconds(<span style="color: rgb(28, 0, 207);">3</span>)); </div>
<div style="margin: 0px; color: rgb(0, 116, 0);"><span style="color: rgb(0, 0, 0);">        <span style="color: rgb(63, 110, 116);">boost</span>::lock_guard&lt;<span style="color: rgb(63, 110, 116);">boost</span>::<span style="color: rgb(63, 110, 116);">mutex</span>&gt; lock(<span style="color: rgb(63, 110, 116);">mutex</span>); </span></div>
<div style="margin: 0px;">        <span style="color: rgb(92, 38, 153);">std</span>::cout &lt;&lt; <span style="color: rgb(196, 26, 22);">&quot;Thread &quot;</span> &lt;&lt; <span style="color: rgb(63, 110, 116);">boost</span>::this_thread::get_id() &lt;&lt; <span style="color: rgb(196, 26, 22);">&quot;: &quot;</span> &lt;&lt; <span style="color: rgb(63, 110, 116);">i</span> &lt;&lt; <span style="color: rgb(92, 38, 153);">std</span>::endl; </div>
<div style="margin: 0px;">    } </div><div style="margin: 0px;">} </div><div style="margin: 0px; min-height: 16px;"><br></div><div style="margin: 0px; min-height: 16px;"><span style="color: rgb(170, 13, 145);">int</span> main(<span style="color: rgb(170, 13, 145);">int</span> argc, <span style="color: rgb(170, 13, 145);">char</span> *argv[]) {</div>
</div><div style="margin: 0px;"><div style="margin: 0px;">    boost::thread t1(thread); </div><div style="margin: 0px;">    boost::thread t2(thread); </div><div style="margin: 0px;">    t1.join(); </div><div style="margin: 0px;">
    t2.join();</div></div><div style="margin: 0px;">}</div><div style="margin: 0px;"><br></div><div style="margin: 0px;">I compile the code with pthread option on the gcc (4.0.1). In the first case the program works, but if I use the helgrind tool of valgrind I&#39;ll get this errors (sorry for the long messages).</div>
<div style="margin: 0px;">I would like to understand what I have done wrong. I hope I understand the lock_guard in the correct way: If I create the lock with the mutex variable the thread, that creates the lock runs down the next lines. All other threads that run into the lock_guard line blocks until the lock variable of the first thread call the destructor (which should be on every loop iteration).  </div>
<div style="margin: 0px;"><br></div><div style="margin: 0px;">Thanks for help</div><div style="margin: 0px;"><br></div><div style="margin: 0px;">Phil</div><div style="margin: 0px;"><br></div><div style="margin: 0px;"><br>
</div><div style="margin: 0px;">------Valgrind Logs-----------</div><div style="margin: 0px;"><br></div><div style="margin: 0px;"><br></div><div style="margin: 0px;">==19846== Thread #1 is the program&#39;s root thread</div>
<div style="margin: 0px;"><br></div><div style="margin: 0px;"><div style="margin: 0px;">==19846== Thread #3 &amp; #2 was created</div><div style="margin: 0px;">==19846==    at 0x15A1FDE: __bsdthread_create (in /usr/lib/libSystem.B.dylib)</div>
<div style="margin: 0px;">==19846==    by 0x378F4: pthread_create_WRK (hg_intercepts.c:257)</div><div style="margin: 0px;">==19846==    by 0x379C8: pthread_create (hg_intercepts.c:294)</div><div style="margin: 0px;">==19846==    by 0x55C06: boost::thread::start_thread() (in libboost_thread.dylib)</div>
<div style="margin: 0px;">==19846==    by 0x9FED: boost::thread::thread&lt;void (*)()&gt;(void (*)(), boost::disable_if&lt;boost::is_convertible&lt;void (*&amp;)(), boost::detail::thread_move_t&lt;void (*)()&gt; &gt;, boost::thread::dummy*&gt;::type) (in ./main)</div>
<div style="margin: 0px;">==19846==    by 0x2A82: main (in ./main)</div><div><br></div><div>This message is show for thread #1, #2 and #3</div><div><br></div><div><div>==19846== Possible data race during read of size 4 at 0x5e008 by thread #3</div>
<div>==19846==    at 0x56381: void boost::call_once&lt;void (*)()&gt;(boost::once_flag&amp;, void (*)()) (in libboost_thread.dylib)</div><div>==19846==    by 0x545AC: thread_proxy (in libboost_thread.dylib)</div><div>==19846==    by 0x37828: mythread_wrapper (hg_intercepts.c:221)</div>
<div>==19846==    by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib)</div><div>==19846==    by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib)</div><div>==19846==  This conflicts with a previous write of size 4 by thread #2</div>
<div>==19846==    at 0x5647F: void boost::call_once&lt;void (*)()&gt;(boost::once_flag&amp;, void (*)()) (in /libboost_thread.dylib)</div><div>==19846==    by 0x545AC: thread_proxy (in /libboost_thread.dylib)</div><div>==19846==    by 0x37828: mythread_wrapper (hg_intercepts.c:221)</div>
<div>==19846==    by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib)</div><div>==19846==    by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib)</div></div><div><br></div><div><div>==19846== Thread #2: Bug in libpthread: recursive write lock granted on mutex/wrlock which does not support recursion</div>
<div>==19846==    at 0x385D2: pthread_cond_timedwait_WRK (hg_intercepts.c:764)</div><div>==19846==    by 0x386B0: pthread_cond_timedwait$* (hg_intercepts.c:798)</div><div>==19846==    by 0x5AABB: boost::condition_variable::timed_wait(boost::unique_lock&lt;boost::mutex&gt;&amp;, boost::posix_time::ptime const&amp;) (in libboost_thread.dylib)</div>
<div>==19846==    by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&amp;) (in libboost_thread.dylib)</div><div>==19846==    by 0xEE31: void boost::this_thread::sleep&lt;boost::posix_time::seconds&gt;(boost::posix_time::seconds const&amp;) (in ./main)</div>
<div>==19846==    by 0x23F8: thread() (in ./main)</div><div>==19846==    by 0x545CC: thread_proxy (in libboost_thread.dylib)</div><div>==19846==    by 0x37828: mythread_wrapper (hg_intercepts.c:221)</div><div>==19846==    by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib)</div>
<div>==19846==    by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib)</div></div><div><br></div><div>The next message is shown for the thread #2 &amp; #3</div><div><br></div><div><div>==19846== Thread #3: lock order &quot;0x2500668 before 0x25005C8&quot; violated</div>
<div>==19846==    at 0x37E1B: pthread_mutex_lock (hg_intercepts.c:496)</div><div>==19846==    by 0x5ABA3: boost::condition_variable::timed_wait(boost::unique_lock&lt;boost::mutex&gt;&amp;, boost::posix_time::ptime const&amp;) (in libboost_thread.dylib)</div>
<div>==19846==    by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&amp;) (in libboost_thread.dylib)</div><div>==19846==    by 0xEE31: void boost::this_thread::sleep&lt;boost::posix_time::seconds&gt;(boost::posix_time::seconds const&amp;) (in ./main)</div>
<div>==19846==    by 0x23F8: thread() (in ./main)</div><div>==19846==    by 0x545CC: thread_proxy (in libboost_thread.dylib)</div><div>==19846==    by 0x37828: mythread_wrapper (hg_intercepts.c:221)</div><div>==19846==    by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib)</div>
<div>==19846==    by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib)</div><div>==19846==   Required order was established by acquisition of lock at 0x2500668</div><div>==19846==    at 0x37E1B: pthread_mutex_lock (hg_intercepts.c:496)</div>
<div>==19846==    by 0x15A3452: _pthread_cond_wait (in /usr/lib/libSystem.B.dylib)</div><div>==19846==    by 0x15C89F7: pthread_cond_timedwait$UNIX2003 (in /usr/lib/libSystem.B.dylib)</div><div>==19846==    by 0x38575: pthread_cond_timedwait_WRK (hg_intercepts.c:760)</div>
<div>==19846==    by 0x386B0: pthread_cond_timedwait$* (hg_intercepts.c:798)</div><div>==19846==    by 0x5AABB: boost::condition_variable::timed_wait(boost::unique_lock&lt;boost::mutex&gt;&amp;, boost::posix_time::ptime const&amp;) (in libboost_thread.dylib)</div>
<div>==19846==    by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&amp;) (in libboost_thread.dylib)</div><div>==19846==    by 0xEE31: void boost::this_thread::sleep&lt;boost::posix_time::seconds&gt;(boost::posix_time::seconds const&amp;) (in ./main)</div>
<div>==19846==    by 0x23F8: thread() (in ./main)</div><div>==19846==    by 0x545CC: thread_proxy (in libboost_thread.dylib)</div><div>==19846==    by 0x37828: mythread_wrapper (hg_intercepts.c:221)</div><div>==19846==    by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib)</div>
<div>==19846==   followed by a later acquisition of lock at 0x25005C8</div><div>==19846==    at 0x37E1B: pthread_mutex_lock (hg_intercepts.c:496)</div><div>==19846==    by 0x53E6A: boost::this_thread::interruption_point() (in libboost_thread.dylib)</div>
<div>==19846==    by 0x5AAC2: boost::condition_variable::timed_wait(boost::unique_lock&lt;boost::mutex&gt;&amp;, boost::posix_time::ptime const&amp;) (in /libboost_thread.dylib)</div><div>==19846==    by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&amp;) (in libboost_thread.dylib)</div>
<div>==19846==    by 0xEE31: void boost::this_thread::sleep&lt;boost::posix_time::seconds&gt;(boost::posix_time::seconds const&amp;) (in ./main)</div><div>==19846==    by 0x23F8: thread() (in ./main)</div><div>==19846==    by 0x545CC: thread_proxy (in libboost_thread.dylib)</div>
<div>==19846==    by 0x37828: mythread_wrapper (hg_intercepts.c:221)</div><div>==19846==    by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib)</div><div>==19846==    by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib)</div>
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