- </p></dd><dt><span class="term">
-
- "<code class="mallctl">swap.avail</code>"
-
- (<span class="type">size_t</span>)
- <code class="literal">r-</code>
- [<code class="option">--enable-stats --enable-swap</code>]
- </span></dt><dd><p>Number of swap file bytes that are currently not
- associated with any chunk (i.e. mapped, but otherwise completely
- unmanaged).</p></dd><dt><a name="swap.prezeroed"></a><span class="term">
-
- "<code class="mallctl">swap.prezeroed</code>"
-
- (<span class="type">bool</span>)
- <code class="literal">rw</code>
- [<code class="option">--enable-swap</code>]
- </span></dt><dd><p>If true, the allocator assumes that the swap file(s)
- contain nothing but nil bytes. If this assumption is violated,
- allocator behavior is undefined. This value becomes read-only after
- <a class="link" href="#swap.fds">
- "<code class="mallctl">swap.fds</code>"
- </a> is
- successfully written to.</p></dd><dt><span class="term">
-
- "<code class="mallctl">swap.nfds</code>"
-
- (<span class="type">size_t</span>)
- <code class="literal">r-</code>
- [<code class="option">--enable-swap</code>]
- </span></dt><dd><p>Number of file descriptors in use for swap.
- </p></dd><dt><a name="swap.fds"></a><span class="term">
-
- "<code class="mallctl">swap.fds</code>"
-
- (<span class="type">int *</span>)
- <code class="literal">r-</code>
- [<code class="option">--enable-swap</code>]
- </span></dt><dd><p>When written to, the files associated with the
- specified file descriptors are contiguously mapped via
- <span class="citerefentry"><span class="refentrytitle">mmap</span>(2)</span>. The resulting virtual memory
- region is preferred over anonymous
- <span class="citerefentry"><span class="refentrytitle">mmap</span>(2)</span> and
- <span class="citerefentry"><span class="refentrytitle">sbrk</span>(2)</span> memory. Note that if a file's
- size is not a multiple of the page size, it is automatically truncated
- to the nearest page size multiple. See the
- <a class="link" href="#swap.prezeroed">
- "<code class="mallctl">swap.prezeroed</code>"
- </a>
- mallctl for specifying that the files are pre-zeroed.</p></dd></dl></div></div><div class="refsect1" title="DEBUGGING MALLOC PROBLEMS"><a name="debugging_malloc_problems"></a><h2>DEBUGGING MALLOC PROBLEMS</h2><p>When debugging, it is a good idea to configure/build jemalloc with