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<title>Berkeley DB Reference Guide: Application signal handling</title>
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<td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Programmer Notes</dl></h3></td>
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<h1 align=center>Application signal handling</h1>
<p>When applications using Berkeley DB receive signals, it is important that they
exit gracefully, discarding any Berkeley DB locks that they may hold. This is
normally done by setting a flag when a signal arrives, and then checking
for that flag periodically within the application. As Berkeley DB is not
reentrant, the signal handler should not attempt to release locks and/or
close the database handles itself. Reentering Berkeley DB is not guaranteed to
work correctly and the results are undefined.
<p>If an application exits holding a lock, the situation is no different
than if the application crashed, and all applications participating in
the database environment must be shutdown, and then recovery must be
performed. If this is not done, databases may be left in an
inconsistent state or locks the application held may cause unresolvable
deadlocks inside the environment, causing applications to hang.
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