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<center><h1>Heap profiling with nhc98</h1></center>
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<p>
Heap profiling allows a programmer to see how heap space is
being used within their program. This can enable space "leaks"
to be identified, and their causes tracked down.
<h3>To obtain a heap profile of a computation:</h3>
<ol>
<li>
<p>Compile all modules of the program with the <tt>-p</tt> option;
also specify <tt>-p</tt> at link-time. Using
<tt>hmake -p</tt> does all the necessary compiling and
linking automatically. eg. to compile <tt>MyProg.hs</tt> and
everything it depends on for heap profiling simply use
<tt>hmake -p MyProg</tt></p></li>
<li>
<p>Run the program with additional runtime arguments:
e.g. <tt>./MyProg +RTS -p -RTS</tt>
to output "producer" heap profile data to the file
<tt>MyProg.hp</tt></p></li>
<li>
<p>Convert the raw profile data to a PostScript graph with
the utility <b>hp2graph</b>, and view it in your favorite
viewer.
</ol>
<br />
<h3>Heap profiling options</h3>
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<tt>-i<i>size</i></tt>
</td><td>
set the profiling interval to <tt><i>size</i></tt>
(in number of allocations, or in seconds)
</td></tr>
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<tt>-p</tt>
</td><td>
select producer profiling
</td></tr>
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<tt>-c</tt>
</td><td>
select construction profiling
</td></tr>
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<tt>-m</tt>
</td><td>
select per-module profiling
</td></tr>
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<tt>-r<em>[num]</em></tt>
</td><td>
select retainer profiling - <em>num</em> is maximum retainer set size
(default=1)
</td></tr>
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<tt>-l</tt>
</td><td>
select lifetime profiling
</td></tr>
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<tt>-b</tt>
</td><td>
select biographical profiling
</td></tr>
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<tt>-p<em>names</em></tt>
</td><td>
restrict profile to named producers
</td></tr>
<tr><td valign="top">
<tt>-c<em>names</em></tt>
</td><td>
restrict profile to named constructions
</td></tr>
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<tt>-m<em>names</em></tt>
</td><td>
restrict profile to named modules
</td></tr>
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<tt>-r<em>names</em></tt>
</td><td>
restrict profile to named retainers
(default=1)
</td></tr>
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<tt>-l<em>nums</em></tt>
</td><td>
restrict profile to numbered lifetimes
(<em>min-</em>, <em>-max</em>, or <em>min-max</em>)
</td></tr>
<tr><td valign="top">
<tt>-b<em>name</em></tt>
</td><td>
restrict profile to named biographical phase
(<em>lag</em>, <em>drag</em>, <em>void</em>, or <em>use</em>)
</td></tr>
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<p>
The first occurrence of
any of the options <em>pcmrbl</em> determines the primary form of the
profile. Subsequent <em>pcmrbl</em> options introduce restrictions on
the profile, for instance <em>-p -c:</em> asks for a producer profile
restricted to producers of the `:' (list) construction. Restrictions
are almost all orthogonal to each other, and you may have as many as
you like. Except for biography and lifetime restrictions, the format
is of a list of names, separated by commas. (In general, you may need to
use quotes around the list to protect special characters from the shell.)
<hr />
<p>
The latest updates to these pages are available on the WWW from
<a href="http://www.haskell.org/nhc98/">
<tt>http://www.haskell.org/nhc98/</tt></a></p>
<p>
<a href="http://www.cs.york.ac.uk/fp/">
York Functional Programming Group</a>
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